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* trace2: add stats for fsync operationsNeeraj Singh2022-03-301-0/+12
| | | | | | | | | | | | Add some global trace2 statistics for the number of fsyncs performed during the lifetime of a Git process. These stats are printed as part of trace2_cmd_exit_fl, which is presumably where we might want to print any other cross-cutting statistics. Signed-off-by: Neeraj Singh <neerajsi@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* core.fsyncmethod: add writeout-only modeNeeraj Singh2022-03-101-0/+64
| | | | | | | | | | | | | | | | | | | | | | | | | | | This commit introduces the `core.fsyncMethod` configuration knob, which can currently be set to `fsync` or `writeout-only`. The new writeout-only mode attempts to tell the operating system to flush its in-memory page cache to the storage hardware without issuing a CACHE_FLUSH command to the storage controller. Writeout-only fsync is significantly faster than a vanilla fsync on common hardware, since data is written to a disk-side cache rather than all the way to a durable medium. Later changes in this patch series will take advantage of this primitive to implement batching of hardware flushes. When git_fsync is called with FSYNC_WRITEOUT_ONLY, it may fail and the caller is expected to do an ordinary fsync as needed. On Apple platforms, the fsync system call does not issue a CACHE_FLUSH directive to the storage controller. This change updates fsync to do fcntl(F_FULLFSYNC) to make fsync actually durable. We maintain parity with existing behavior on Apple platforms by setting the default value of the new core.fsyncMethod option. Signed-off-by: Neeraj Singh <neerajsi@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* wrapper: make inclusion of Windows csprng header tightly scopedNeeraj Singh2022-03-101-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Including NTSecAPI.h in git-compat-util.h causes build errors in any other file that includes winternl.h. NTSecAPI.h was included in order to get access to the RtlGenRandom cryptographically secure PRNG. This change scopes the inclusion of ntsecapi.h to wrapper.c, which is the only place that it's actually needed. The build breakage is due to the definition of UNICODE_STRING in NtSecApi.h: #ifndef _NTDEF_ typedef LSA_UNICODE_STRING UNICODE_STRING, *PUNICODE_STRING; typedef LSA_STRING STRING, *PSTRING ; #endif LsaLookup.h: typedef struct _LSA_UNICODE_STRING { USHORT Length; USHORT MaximumLength; #ifdef MIDL_PASS [size_is(MaximumLength/2), length_is(Length/2)] #endif // MIDL_PASS PWSTR Buffer; } LSA_UNICODE_STRING, *PLSA_UNICODE_STRING; winternl.h also defines UNICODE_STRING: typedef struct _UNICODE_STRING { USHORT Length; USHORT MaximumLength; PWSTR Buffer; } UNICODE_STRING; typedef UNICODE_STRING *PUNICODE_STRING; Both definitions have equivalent layouts. Apparently these internal Windows headers aren't designed to be included together. This is an oversight in the headers and does not represent an incompatibility between the APIs. Signed-off-by: Neeraj Singh <neerajsi@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* wrapper: use a CSPRNG to generate random file namesbrian m. carlson2022-01-171-11/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The current way we generate random file names is by taking the seconds and microseconds, plus the PID, and mixing them together, then encoding them. If this fails, we increment the value by 7777, and try again up to TMP_MAX times. Unfortunately, this is not the best idea from a security perspective. If we're writing into TMPDIR, an attacker can guess these values easily and prevent us from creating any temporary files at all by creating them all first. Even though we set TMP_MAX to 16384, this may be achievable in some contexts, even if unlikely to occur in practice. Fortunately, we can simply solve this by using the system cryptographically secure pseudorandom number generator (CSPRNG) to generate a random 64-bit value, and use that as before. Note that there is still a small bias here, but because a six-character sequence chosen out of 62 characters provides about 36 bits of entropy, the bias here is less than 2^-28, which is acceptable, especially considering we'll retry several times. Note that the use of a CSPRNG in generating temporary file names is also used in many libcs. glibc recently changed from an approach similar to ours to using a CSPRNG, and FreeBSD and OpenBSD also use a CSPRNG in this case. Even if the likelihood of an attack is low, we should still be at least as responsible in creating temporary files as libc is. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* wrapper: add a helper to generate numbers from a CSPRNGbrian m. carlson2022-01-171-0/+66
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are many situations in which having access to a cryptographically secure pseudorandom number generator (CSPRNG) is helpful. In the future, we'll encounter one of these when dealing with temporary files. To make this possible, let's add a function which reads from a system CSPRNG and returns some bytes. We know that all systems will have such an interface. A CSPRNG is required for a secure TLS or SSH implementation and a Git implementation which provided neither would be of little practical use. In addition, POSIX is set to standardize getentropy(2) in the next version, so in the (potentially distant) future we can rely on that. For systems which lack one of the other interfaces, we provide the ability to use OpenSSL's CSPRNG. OpenSSL is highly portable and functions on practically every known OS, and we know it will have access to some source of cryptographically secure randomness. We also provide support for the arc4random in libbsd for folks who would prefer to use that. Because this is a security sensitive interface, we take some precautions. We either succeed by filling the buffer completely as we requested, or we fail. We don't return partial data because the caller will almost never find that to be a useful behavior. Specify a makefile knob which users can use to specify one or more suitable CSPRNGs, and turn the multiple string options into a set of defines, since we cannot match on strings in the preprocessor. We allow multiple options to make the job of handling this in autoconf easier. The order of options is important here. On systems with arc4random, which is most of the BSDs, we use that, since, except on MirBSD and macOS, it uses ChaCha20, which is extremely fast, and sits entirely in userspace, avoiding a system call. We then prefer getrandom over getentropy, because the former has been available longer on Linux, and then OpenSSL. Finally, if none of those are available, we use /dev/urandom, because most Unix-like operating systems provide that API. We prefer options that don't involve device files when possible because those work in some restricted environments where device files may not be available. Set the configuration variables appropriately for Linux and the BSDs, including macOS, as well as Windows and NonStop. We specifically only consider versions which receive publicly available security support here. For the same reason, we don't specify getrandom(2) on Linux, because CentOS 7 doesn't support it in glibc (although its kernel does) and we don't want to resort to making syscalls. Finally, add a test helper to allow this to be tested by hand and in tests. We don't add any tests, since invoking the CSPRNG is not likely to produce interesting, reproducible results. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* wrapper: remove xunsetenv()Carlo Marcelo Arenas Belón2021-10-291-6/+0
| | | | | | | | Remove the unused wrapper function. Reported-by: Randall S. Becker <rsbecker@nexbridge.com> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* wrapper.c: add x{un,}setenv(), and use xsetenv() in environment.cÆvar Arnfjörð Bjarmason2021-09-221-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add fatal wrappers for setenv() and unsetenv(). In d7ac12b25d3 (Add set_git_dir() function, 2007-08-01) we started checking its return value, and since 48988c4d0c3 (set_git_dir: die when setenv() fails, 2018-03-30) we've had set_git_dir_1() die if we couldn't set it. Let's provide a wrapper for both, this will be useful in many other places, a subsequent patch will make another use of xsetenv(). The checking of the return value here is over-eager according to setenv(3) and POSIX. It's documented as returning just -1 or 0, so perhaps we should be checking -1 explicitly. Let's just instead die on any non-zero, if our C library is so broken as to return something else than -1 on error (and perhaps not set errno?) the worst we'll do is die with a nonsensical errno value, but we'll want to die in either case. Let's make these return "void" instead of "int". As far as I can tell there's no other x*() wrappers that needed to make the decision of deviating from the signature in the C library, but since their return value is only used to indicate errors (so we'd die here), we can catch unreachable code such as if (xsetenv(...) < 0) [...]; I think it would be OK skip the NULL check of the "name" here for the calls to die_errno(). Almost all of our setenv() callers are taking a constant string hardcoded in the source as the first argument, and for the rest we can probably assume they've done the NULL check themselves. Even if they didn't, modern C libraries are forgiving about it (e.g. glibc formatting it as "(null)"), on those that aren't, well, we were about to die anyway. But let's include the check anyway for good measure. 1. https://pubs.opengroup.org/onlinepubs/009604499/functions/setenv.html Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* xopen: explicitly report creation failuresRené Scharfe2021-08-251-1/+3
| | | | | | | | | | | | | | | | | | | If the flags O_CREAT and O_EXCL are both given then open(2) is supposed to create the file and error out if it already exists. The error message in that case looks like this: fatal: could not open 'foo' for writing: File exists Without further context this is confusing: Why should the existence of the file pose a problem? Isn't that a requirement for writing to it? Add a more specific error message for that case to tell the user that we actually don't expect the file to preexist, so the example becomes: fatal: unable to create 'foo': File exists Signed-off-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* add open_nofollow() helperJeff King2021-02-161-0/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some callers of open() would like to use O_NOFOLLOW, but it is not available on all platforms. Let's abstract this into a helper function so we can provide system-specific implementations. Some light web-searching reveals that we might be able to get something similar on Windows using FILE_FLAG_OPEN_REPARSE_POINT. I didn't dig into this further. For other systems without O_NOFOLLOW or any equivalent, we have two options for fallback: - we can just open anyway, following symlinks; this may have security implications (e.g., following untrusted in-tree symlinks) - we can determine whether the path is a symlink with lstat(). This is slower (two syscalls instead of one), but that may be acceptable for infrequent uses like looking up .gitattributes files (especially because we can get away with a single syscall for the common case of ENOENT). It's also racy, but should be sufficient for our needs (we are worried about in-tree symlinks that we ourselves would have previously created). We could make it non-racy at the cost of making it even slower, by doing an fstat() on the opened descriptor and comparing the dev/ino fields to the original lstat(). This patch implements the lstat() option in its slightly-faster racy form. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* xrealloc: do not reuse pointer freed by zero-length realloc()Jeff King2020-09-021-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch fixes a bug where xrealloc(ptr, 0) can double-free and corrupt the heap on some platforms (including at least glibc). The C99 standard says of malloc (section 7.20.3): If the size of the space requested is zero, the behavior is implementation-defined: either a null pointer is returned, or the behavior is as if the size were some nonzero value, except that the returned pointer shall not be used to access an object. So we might get NULL back, or we might get an actual pointer (but we're not allowed to look at its contents). To simplify our code, our xmalloc() handles a NULL return by converting it into a single-byte allocation. That way callers get consistent behavior. This was done way back in 4e7a2eccc2 (?alloc: do not return NULL when asked for zero bytes, 2005-12-29). We also gave xcalloc() and xrealloc() the same treatment. And according to C99, that is fine; the text above is in a paragraph that applies to all three. But what happens to the memory we passed to realloc() in such a case? I.e., if we do: ret = realloc(ptr, 0); and "ptr" is non-NULL, but we get NULL back, is "ptr" still valid? C99 doesn't cover this case specifically, but says (section 7.20.3.4): The realloc function deallocates the old object pointed to by ptr and returns a pointer to a new object that has the size specified by size. So "ptr" is now deallocated, and we must only look at "ret". And since "ret" is NULL, that means we have no allocated object at all. But that's not quite the whole story. It also says: If memory for the new object cannot be allocated, the old object is not deallocated and its value is unchanged. [...] The realloc function returns a pointer to the new object (which may have the same value as a pointer to the old object), or a null pointer if the new object could not be allocated. So if we see a NULL return with a non-zero size, we can expect that the original object _is_ still valid. But with a non-zero size, it's ambiguous. The NULL return might mean a failure (in which case the object is valid), or it might mean that we successfully allocated nothing, and used NULL to represent that. The glibc manpage for realloc() explicitly says: [...]if size is equal to zero, and ptr is not NULL, then the call is equivalent to free(ptr). Likewise, this StackOverflow answer: https://stackoverflow.com/a/2135302 claims that C89 gave similar guidance (but I don't have a copy to verify it). A comment on this answer: https://stackoverflow.com/a/2022410 claims that Microsoft's CRT behaves the same. But our current "retry with 1 byte" code passes the original pointer again. So on glibc, we effectively free() the pointer and then try to realloc() it again, which is undefined behavior. The simplest fix here is to just pass "ret" (which we know to be NULL) to the follow-up realloc(). But that means that a system which _doesn't_ free the original pointer would leak it. It's not clear if any such systems exist, and that interpretation of the standard seems unlikely (I'd expect a system that doesn't deallocate to simply return the original pointer in this case). But it's easy enough to err on the safe side, and just never pass a zero size to realloc() at all. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* wrapper: add function to compare strings with different NUL terminationbrian m. carlson2020-05-271-0/+8
| | | | | | | | | | | | | | | | | When parsing capabilities for the pack protocol, there are times we'll want to compare the value of a capability to a NUL-terminated string. Since the data we're reading will be space-terminated, not NUL-terminated, we need a function that compares the two strings, but also checks that they're the same length. Otherwise, if we used strncmp to compare these strings, we might accidentally accept a parameter that was a prefix of the expected value. Add a function, xstrncmpz, that takes a NUL-terminated string and a non-NUL-terminated string, plus a length, and compares them, ensuring that they are the same length. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* Merge branch 'dl/wrapper-fix-indentation'Junio C Hamano2020-04-221-2/+2
|\ | | | | | | | | | | | | Coding style fix. * dl/wrapper-fix-indentation: wrapper: indent with tabs
| * wrapper: indent with tabsDenton Liu2020-03-281-2/+2
| | | | | | | | | | | | | | | | The codebase uses tabs for indentation. Convert an erroneous space indent into a tab indent. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Merge branch 'ah/cleanups'Junio C Hamano2019-10-091-10/+11
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | Miscellaneous code clean-ups. * ah/cleanups: git_mkstemps_mode(): replace magic numbers with computed value wrapper: use a loop instead of repetitive statements diffcore-break: use a goto instead of a redundant if statement commit-graph: remove a duplicate assignment
| * | git_mkstemps_mode(): replace magic numbers with computed valueJeff King2019-10-031-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The magic number "6" appears several times in the function, and is related to the size of the "XXXXXX" string we expect to find in the template. Let's pull that "XXXXXX" into a constant array, whose size we can get at compile time with ARRAY_SIZE(). Note that we probably can't just change this value, since callers will be feeding us a certain number of X's, but it hopefully makes the function itself easier to follow. While we're here, let's do the same with the "letters" array (which we _could_ modify if we wanted to include more characters). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | wrapper: use a loop instead of repetitive statementsAlex Henrie2019-10-021-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A check into the history of this code revealed no particular reason for the code to be written in this way. All popular compilers are capable of unrolling loops if it benefits performance, and once this code is replaced with a loop, the magic number 6 used in multiple places in this function can be replaced with a named constant. Reviewed-by: Derrick Stolee <stolee@gmail.com> Reviewed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Alex Henrie <alexhenrie24@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | packfile: drop release_pack_memory()Jeff King2019-08-131-50/+13
|/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Long ago, in 97bfeb34df (Release pack windows before reporting out of memory., 2006-12-24), we taught xmalloc() and friends to try unmapping pack windows when malloc() failed. It's unlikely that his helps a lot in practice, and it has some downsides. First, the downsides: 1. It makes xmalloc() not thread-safe. We've worked around this in pack-objects.c, which installs its own locking version of the try_to_free_routine(). But other threaded code doesn't. 2. It makes the system as a whole harder to reason about. Functions which allocate heap memory under the hood may have farther-reaching effects than expected. That might be worth the tradeoff if there's a benefit. But in practice, it seems unlikely. We're generally dealing with mmap'd files, so the OS is going to do a much better job at responding to memory pressure by dropping individual pages (the exception is systems with NO_MMAP, but even there the OS can probably respond just as well with swapping). So the only thing we're really freeing is address space. On 64-bit systems, we have plenty of that to go around. On 32-bit systems, it could possibly help. But around the same time we made two other changes: 77ccc5bbd1 (Introduce new config option for mmap limit., 2006-12-23) and 60bb8b1453 (Fully activate the sliding window pack access., 2006-12-23). Together that means that a 32-bit system should have no more than 256MB total of packed-git mmaps at one time, split between a few 32MB windows. It's unlikely we have any address space problems since then, but we don't have any data since the features were all added at the same time. Likewise, xmmap() will try to free memory. At first glance, it seems like we'd need this (when we try to mmap a new window, we might need to close an old one to save address space on a 32-bit system). But we're saved again by core.packedGitLimit: if we're going to exceed our 256MB limit, we'll close an existing window before we even call mmap(). So it seems unlikely that this feature is actually doing anything useful. And while we don't have reports of it harming anything (probably because it rarely if ever kicks in), it would be nice to simplify the system overall. This patch drops the whole try_to_free system from xmalloc(), as well as the manual pack memory release in xmmap(). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | wrapper: avoid undefined behaviour in macOSCarlo Marcelo Arenas Belón2019-06-191-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 0620b39b3b ("compat: add a mkstemps() compatibility function", 2009-05-31) included a function based on code from libiberty which would result in undefined behaviour in platforms where timeval's tv_usec is a 32-bit signed type as shown by: wrapper.c:505:31: runtime error: left shift of 594546 by 16 places cannot be represented in type '__darwin_suseconds_t' (aka 'int') interestingly the version of this code from gcc never had this bug and the code had a cast that would had prevented the issue (at least in 64-bit platforms) but was misapplied. change the cast to uint64_t so it also works in 32-bit platforms. Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | wrapper: move is_empty_file() and rename it as is_empty_or_missing_file()Pranit Bauva2019-01-021-0/+13
| | | | | | | | | | | | | | | | | | | | | | is_empty_file() can help to refactor a lot of code. This will be very helpful in porting "git bisect" to C. Suggested-by: Torsten Bögershausen <tboegi@web.de> Mentored-by: Lars Schneider <larsxschneider@gmail.com> Mentored-by: Christian Couder <chriscool@tuxfamily.org> Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Replace all die("BUG: ...") calls by BUG() onesJohannes Schindelin2018-05-061-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In d8193743e08 (usage.c: add BUG() function, 2017-05-12), a new macro was introduced to use for reporting bugs instead of die(). It was then subsequently used to convert one single caller in 588a538ae55 (setup_git_env: convert die("BUG") to BUG(), 2017-05-12). The cover letter of the patch series containing this patch (cf 20170513032414.mfrwabt4hovujde2@sigill.intra.peff.net) is not terribly clear why only one call site was converted, or what the plan is for other, similar calls to die() to report bugs. Let's just convert all remaining ones in one fell swoop. This trick was performed by this invocation: sed -i 's/die("BUG: /BUG("/g' $(git grep -l 'die("BUG' \*.c) Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | wrapper: rename 'template' variablesBrandon Williams2018-02-221-20/+20
| | | | | | | | | | | | | | | | Rename C++ keyword in order to bring the codebase closer to being able to be compiled with a C++ compiler. Signed-off-by: Brandon Williams <bmwill@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | wrapper.c: consistently quote filenames in error messagessr/wrapper-quote-filenamesSimon Ruderich2017-11-061-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | All other error messages in the file use quotes around the file name. This change removes two translations as "could not write to '%s'" and "could not close '%s'" are already translated and these two are the only occurrences without quotes. Signed-off-by: Simon Ruderich <simon@ruderich.org> [jc: adjusted tests I noticed were broken by the change] Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | avoid "write_in_full(fd, buf, len) != len" patternJeff King2017-09-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The return value of write_in_full() is either "-1", or the requested number of bytes[1]. If we make a partial write before seeing an error, we still return -1, not a partial value. This goes back to f6aa66cb95 (write_in_full: really write in full or return error on disk full., 2007-01-11). So checking anything except "was the return value negative" is pointless. And there are a couple of reasons not to do so: 1. It can do a funny signed/unsigned comparison. If your "len" is signed (e.g., a size_t) then the compiler will promote the "-1" to its unsigned variant. This works out for "!= len" (unless you really were trying to write the maximum size_t bytes), but is a bug if you check "< len" (an example of which was fixed recently in config.c). We should avoid promoting the mental model that you need to check the length at all, so that new sites are not tempted to copy us. 2. Checking for a negative value is shorter to type, especially when the length is an expression. 3. Linus says so. In d34cf19b89 (Clean up write_in_full() users, 2007-01-11), right after the write_in_full() semantics were changed, he wrote: I really wish every "write_in_full()" user would just check against "<0" now, but this fixes the nasty and stupid ones. Appeals to authority aside, this makes it clear that writing it this way does not have an intentional benefit. It's a historical curiosity that we never bothered to clean up (and which was undoubtedly cargo-culted into new sites). So let's convert these obviously-correct cases (this includes write_str_in_full(), which is just a wrapper for write_in_full()). [1] A careful reader may notice there is one way that write_in_full() can return a different value. If we ask write() to write N bytes and get a return value that is _larger_ than N, we could return a larger total. But besides the fact that this would imply a totally broken version of write(), it would already invoke undefined behavior. Our internal remaining counter is an unsigned size_t, which means that subtracting too many byte will wrap it around to a very large number. So we'll instantly begin reading off the end of the buffer, trying to write gigabytes (or petabytes) of data. Signed-off-by: Jeff King <peff@peff.net> Reviewed-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Merge branch 'bw/config-h'Junio C Hamano2017-06-241-0/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix configuration codepath to pay proper attention to commondir that is used in multi-worktree situation, and isolate config API into its own header file. * bw/config-h: config: don't implicitly use gitdir or commondir config: respect commondir setup: teach discover_git_directory to respect the commondir config: don't include config.h by default config: remove git_config_iter config: create config.h
| * | config: don't include config.h by defaultBrandon Williams2017-06-151-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | Stop including config.h by default in cache.h. Instead only include config.h in those files which require use of the config system. Signed-off-by: Brandon Williams <bmwill@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | Merge branch 'nd/fopen-errors'Junio C Hamano2017-06-131-5/+26
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We often try to open a file for reading whose existence is optional, and silently ignore errors from open/fopen; report such errors if they are not due to missing files. * nd/fopen-errors: mingw_fopen: report ENOENT for invalid file names mingw: verify that paths are not mistaken for remote nicknames log: fix memory leak in open_next_file() rerere.c: move error_errno() closer to the source system call print errno when reporting a system call error wrapper.c: make warn_on_inaccessible() static wrapper.c: add and use fopen_or_warn() wrapper.c: add and use warn_on_fopen_errors() config.mak.uname: set FREAD_READS_DIRECTORIES for Darwin, too config.mak.uname: set FREAD_READS_DIRECTORIES for Linux and FreeBSD clone: use xfopen() instead of fopen() use xfopen() in more places git_fopen: fix a sparse 'not declared' warning
| * | | wrapper.c: make warn_on_inaccessible() staticNguyễn Thái Ngọc Duy2017-05-261-5/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | After the last patch, this function is not used outside anymore. Keep it static. Noticed-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | | wrapper.c: add and use fopen_or_warn()Nguyễn Thái Ngọc Duy2017-05-261-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When fopen() returns NULL, it could be because the given path does not exist, but it could also be some other errors and the caller has to check. Add a wrapper so we don't have to repeat the same error check everywhere. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | | wrapper.c: add and use warn_on_fopen_errors()Nguyễn Thái Ngọc Duy2017-05-261-0/+10
| |/ / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In many places, Git warns about an inaccessible file after a fopen() failed. To discern these cases from other cases where we want to warn about inaccessible files, introduce a new helper specifically to test whether fopen() failed because the current user lacks the permission to open file in question. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | Merge branch 'jc/noent-notdir'Junio C Hamano2017-06-131-2/+2
|\ \ \ | |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Our code often opens a path to an optional file, to work on its contents when we can successfully open it. We can ignore a failure to open if such an optional file does not exist, but we do want to report a failure in opening for other reasons (e.g. we got an I/O error, or the file is there, but we lack the permission to open). The exact errors we need to ignore are ENOENT (obviously) and ENOTDIR (less obvious). Instead of repeating comparison of errno with these two constants, introduce a helper function to do so. * jc/noent-notdir: treewide: use is_missing_file_error() where ENOENT and ENOTDIR are checked compat-util: is_missing_file_error()
| * | treewide: use is_missing_file_error() where ENOENT and ENOTDIR are checkedjc/noent-notdirJunio C Hamano2017-05-301-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Using the is_missing_file_error() helper introduced in the previous step, update all hits from $ git grep -e ENOENT --and -e ENOTDIR There are codepaths that only check ENOENT, and it is possible that some of them should be checking both. Updating them is kept out of this step deliberately, as we do not want to change behaviour in this step. Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | Merge branch 'dt/xgethostname-nul-termination'Junio C Hamano2017-04-231-0/+13
|\ \ \ | |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | gethostname(2) may not NUL terminate the buffer if hostname does not fit; unfortunately there is no easy way to see if our buffer was too small, but at least this will make sure we will not end up using garbage past the end of the buffer. * dt/xgethostname-nul-termination: xgethostname: handle long hostnames use HOST_NAME_MAX to size buffers for gethostname(2)
| * | xgethostname: handle long hostnamesdt/xgethostname-nul-terminationDavid Turner2017-04-181-0/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If the full hostname doesn't fit in the buffer supplied to gethostname, POSIX does not specify whether the buffer will be null-terminated, so to be safe, we should do it ourselves. Introduce new function, xgethostname, which ensures that there is always a \0 at the end of the buffer. Signed-off-by: David Turner <dturner@twosigma.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | wrapper.c: remove unused gitmkstemps() functionrj/remove-unused-mktempRamsay Jones2017-02-281-7/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The last call to the mkstemps() function was removed in commit 659488326 ("wrapper.c: delete dead function git_mkstemps()", 22-04-2016). In order to support platforms without mkstemps(), this functionality was provided, along with a Makefile build variable (NO_MKSTEMPS), by the gitmkstemps() function. Remove the dead code, along with the defunct build machinery. Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | wrapper.c: remove unused git_mkstemp() functionRamsay Jones2017-02-281-17/+0
|/ / | | | | | | | | | | | | | | | | | | | | | | The last caller of git_mkstemp() was removed in commit 6fec0a89 ("verify_signed_buffer: use tempfile object", 16-06-2016). Since the introduction of the 'tempfile' APIs, along with git_mkstemp_mode, it is unlikely that new callers will materialize. Remove the dead code. Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | Merge branch 'jk/write-file'Junio C Hamano2016-07-191-40/+12
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | General code clean-up around a helper function to write a single-liner to a file. * jk/write-file: branch: use write_file_buf instead of write_file use write_file_buf where applicable write_file: add format attribute write_file: add pointer+len variant write_file: use xopen write_file: drop "gently" form branch: use non-gentle write_file for branch description am: ignore return value of write_file() config: fix bogus fd check when setting up default config
| * | write_file: add pointer+len variantJeff King2016-07-081-5/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are many callsites which could use write_file, but for which it is a little awkward because they have a strbuf or other pointer/len combo. Specifically: 1. write_file() takes a format string, so we have to use "%s" or "%.*s", which are ugly. 2. Using any form of "%s" does not handle embedded NULs in the output. That probably doesn't matter for our call-sites, but it's nicer not to have to worry. 3. It's less efficient; we format into another strbuf just to do the write. That's probably not measurably slow for our uses, but it's simply inelegant. We can fix this by providing a helper to write out the formatted buffer, and just calling it from write_file(). Note that we don't do the usual "complete with a newline" that write_file does. If the caller has their own buffer, there's a reasonable chance they're doing something more complicated than a single line, and they can call strbuf_complete_line() themselves. We could go even further and add strbuf_write_file(), but it doesn't save much: - write_file_buf(path, sb.buf, sb.len); + strbuf_write_file(&sb, path); It would also be somewhat asymmetric with strbuf_read_file, which actually returns errors rather than dying (and the error handling is most of the benefit of write_file() in the first place). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | write_file: use xopenJeff King2016-07-081-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This simplifies the code a tiny bit, and provides consistent error messages with other users of xopen(). While we're here, let's also switch to using O_WRONLY. We know we're only going to open/write/close the file, so there's no point in asking for O_RDWR. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | write_file: drop "gently" formJeff King2016-07-081-43/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are no callers left of write_file_gently(). Let's drop it, as it doesn't seem likely for new callers to be added (since its inception, the only callers who wanted the gentle form generally just died immediately themselves, and have since been converted). While we're there, let's also drop the "int" return from write_file, as it is never meaningful (in the non-gentle form, we always either die or return 0). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | Merge branch 'sb/submodule-parallel-fetch'Junio C Hamano2016-07-191-16/+27
|\ \ \ | |/ / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix recently introduced codepaths that are involved in parallel submodule operations, which gave up on reading too early, and could have wasted CPU while attempting to write under a corner case condition. * sb/submodule-parallel-fetch: hoist out handle_nonblock function for xread and xwrite xwrite: poll on non-blocking FDs xread: retry after poll on EAGAIN/EWOULDBLOCK
| * | hoist out handle_nonblock function for xread and xwritesb/submodule-parallel-fetchEric Wong2016-07-111-28/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | At least for me, this improves the readability of xread and xwrite; hopefully allowing missing "continue" statements to be spotted more easily. Signed-off-by: Eric Wong <e@80x24.org> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | xwrite: poll on non-blocking FDsEric Wong2016-06-271-2/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | write(2) can hit the same EAGAIN/EWOULDBLOCK errors as read(2), so busy-looping on a non-blocking FD is a waste of resources. Currently, I do not know of a way for this happen: * the NonBlocking directive in systemd does not apply to stdin, stdout, or stderr. * xinetd provides no way to set the non-blocking flag at all But theoretically, it's possible a careless C10K HTTP server could use pipe2(..., O_NONBLOCK) to setup a pipe for git-http-backend with only the intent to use non-blocking reads; but accidentally leave non-blocking set on the write end passed as stdout to git-upload-pack. Followup-to: 1079c4be0b720 ("xread: poll on non blocking fds") Signed-off-by: Eric Wong <e@80x24.org> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | xread: retry after poll on EAGAIN/EWOULDBLOCKEric Wong2016-06-271-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We should continue to loop after EAGAIN/EWOULDBLOCK as the intent of xread is to try until there is available data, EOF, or an unrecoverable error. Fixes: 1079c4be0b720 ("xread: poll on non blocking fds") Signed-off-by: Eric Wong <e@80x24.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | Merge branch 'nd/error-errno'Junio C Hamano2016-05-171-2/+2
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The code for warning_errno/die_errno has been refactored and a new error_errno() reporting helper is introduced. * nd/error-errno: (41 commits) wrapper.c: use warning_errno() vcs-svn: use error_errno() upload-pack.c: use error_errno() unpack-trees.c: use error_errno() transport-helper.c: use error_errno() sha1_file.c: use {error,die,warning}_errno() server-info.c: use error_errno() sequencer.c: use error_errno() run-command.c: use error_errno() rerere.c: use error_errno() and warning_errno() reachable.c: use error_errno() mailmap.c: use error_errno() ident.c: use warning_errno() http.c: use error_errno() and warning_errno() grep.c: use error_errno() gpg-interface.c: use error_errno() fast-import.c: use error_errno() entry.c: use error_errno() editor.c: use error_errno() diff-no-index.c: use error_errno() ...
| * | | wrapper.c: use warning_errno()nd/error-errnoNguyễn Thái Ngọc Duy2016-05-091-2/+2
| | | | | | | | | | | | | | | | | | | | Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | | wrapper.c: delete dead function git_mkstemps()nd/remove-unusedNguyễn Thái Ngọc Duy2016-04-221-17/+0
|/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | Its last call site was replaced by mks_tempfile_ts() in 284098f (diff: use tempfile module - 2015-08-12) and there's a good chance mks_tempfile_ts will continue to successfully handle this job. Delete it. Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
* | | Merge branch 'jk/tighten-alloc'Junio C Hamano2016-02-261-0/+3
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Update various codepaths to avoid manually-counted malloc(). * jk/tighten-alloc: (22 commits) ewah: convert to REALLOC_ARRAY, etc convert ewah/bitmap code to use xmalloc diff_populate_gitlink: use a strbuf transport_anonymize_url: use xstrfmt git-compat-util: drop mempcpy compat code sequencer: simplify memory allocation of get_message test-path-utils: fix normalize_path_copy output buffer size fetch-pack: simplify add_sought_entry fast-import: simplify allocation in start_packfile write_untracked_extension: use FLEX_ALLOC helper prepare_{git,shell}_cmd: use argv_array use st_add and st_mult for allocation size computation convert trivial cases to FLEX_ARRAY macros use xmallocz to avoid size arithmetic convert trivial cases to ALLOC_ARRAY convert manual allocations to argv_array argv-array: add detach function add helpers for allocating flex-array structs harden REALLOC_ARRAY and xcalloc against size_t overflow tree-diff: catch integer overflow in combine_diff_path allocation ...
| * | | harden REALLOC_ARRAY and xcalloc against size_t overflowJeff King2016-02-221-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | REALLOC_ARRAY inherently involves a multiplication which can overflow size_t, resulting in a much smaller buffer than we think we've allocated. We can easily harden it by using st_mult() to check for overflow. Likewise, we can add ALLOC_ARRAY to do the same thing for xmalloc calls. xcalloc() should already be fine, because it takes the two factors separately, assuming the system calloc actually checks for overflow. However, before we even hit the system calloc(), we do our memory_limit_check, which involves a multiplication. Let's check for overflow ourselves so that this limit cannot be bypassed. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
| * | | Merge branch 'js/fopen-harder' into maintJunio C Hamano2016-02-051-0/+13
| |\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some codepaths used fopen(3) when opening a fixed path in $GIT_DIR (e.g. COMMIT_EDITMSG) that is meant to be left after the command is done. This however did not work well if the repository is set to be shared with core.sharedRepository and the umask of the previous user is tighter. They have been made to work better by calling unlink(2) and retrying after fopen(3) fails with EPERM. * js/fopen-harder: Handle more file writes correctly in shared repos commit: allow editing the commit message even in shared repos
* | \ \ \ Merge branch 'js/fopen-harder'Junio C Hamano2016-01-201-0/+13
|\ \ \ \ \ | | |/ / / | |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Some codepaths used fopen(3) when opening a fixed path in $GIT_DIR (e.g. COMMIT_EDITMSG) that is meant to be left after the command is done. This however did not work well if the repository is set to be shared with core.sharedRepository and the umask of the previous user is tighter. They have been made to work better by calling unlink(2) and retrying after fopen(3) fails with EPERM. * js/fopen-harder: Handle more file writes correctly in shared repos commit: allow editing the commit message even in shared repos