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| author | Paul Eggert <eggert@cs.ucla.edu> | 2018-02-20 13:42:20 -0800 |
|---|---|---|
| committer | Paul Eggert <eggert@cs.ucla.edu> | 2018-02-20 13:45:27 -0800 |
| commit | d599dce1353ce59d134fcff21cde02c70025253d (patch) | |
| tree | f209e4f35cc4afd930eca9ba14958d92dd33fe42 /src/sysdep.c | |
| parent | 630da78a3cc2a5df2d61e1edf0c209b806b336e2 (diff) | |
| download | emacs-d599dce1353ce59d134fcff21cde02c70025253d.tar.gz | |
Port recent MAX_RW_COUNT checks to POSIX
* src/sysdep.c (MAX_RW_COUNT): Verify that it fits in POSIX standard
types, to go along with already-existing checks for MS-Windows types.
(emacs_intr_read): eassert on all platforms, not just MS-Windows.
Diffstat (limited to 'src/sysdep.c')
| -rw-r--r-- | src/sysdep.c | 29 |
1 files changed, 19 insertions, 10 deletions
diff --git a/src/sysdep.c b/src/sysdep.c index 08db376b261..c59034ce5c3 100644 --- a/src/sysdep.c +++ b/src/sysdep.c @@ -2554,6 +2554,22 @@ emacs_close (int fd) #define MAX_RW_COUNT (INT_MAX >> 18 << 18) #endif +/* Verify that MAX_RW_COUNT fits in the relevant standard types. */ +#ifndef SSIZE_MAX +# define SSIZE_MAX TYPE_MAXIMUM (ssize_t) +#endif +verify (MAX_RW_COUNT <= PTRDIFF_MAX); +verify (MAX_RW_COUNT <= SIZE_MAX); +verify (MAX_RW_COUNT <= SSIZE_MAX); + +#ifdef WINDOWSNT +/* Verify that Emacs read requests cannot cause trouble, even in + 64-bit builds. The last argument of 'read' is 'unsigned int', and + the return value's type (see 'sys_read') is 'int'. */ +verify (MAX_RW_COUNT <= INT_MAX); +verify (MAX_RW_COUNT <= UINT_MAX); +#endif + /* Read from FD to a buffer BUF with size NBYTE. If interrupted, process any quits and pending signals immediately if INTERRUPTIBLE, and then retry the read unless quitting. @@ -2562,18 +2578,11 @@ emacs_close (int fd) static ptrdiff_t emacs_intr_read (int fd, void *buf, ptrdiff_t nbyte, bool interruptible) { + /* No caller should ever pass a too-large size to emacs_read. */ + eassert (nbyte <= MAX_RW_COUNT); + ssize_t result; - /* There is no need to check against MAX_RW_COUNT, since no caller ever - passes a size that large to emacs_read. */ -#ifdef WINDOWSNT - /* On MS-Windows, 'read's last argument is declared as 'unsigned - int', and the return value's type (see 'sys_read') is 'int'. - This might cause trouble, especially in 64-bit builds, if the - above comment ever becomes incorrect. The following assertion - should make us more future-proof. */ - eassert (nbyte <= INT_MAX); -#endif do { if (interruptible) |