Shrink the git binary a bit by avoiding unnecessary inline functions

So I was looking at the disgusting size of the git binary, and even with
the debugging removed, and using -Os instead of -O2, the size of the text
section was pretty high. In this day and age I guess almost a megabyte of
text isn't really all that surprising, but it still doesn't exactly make
me think "lean and mean".

With -Os, a surprising amount of text space is wasted on inline functions
that end up just being replicated multiple times, and where performance
really isn't a valid reason to inline them. In particular, the trivial
wrapper functions like "xmalloc()" are used _everywhere_, and making them
inline just duplicates the text (and the string we use to 'die()' on
failure) unnecessarily.

So this just moves them into a "wrapper.c" file, getting rid of a tiny bit
of unnecessary bloat. The following numbers are both with "CFLAGS=-Os":

Before:
	[torvalds@woody git]$ size git
	   text	   data	    bss	    dec	    hex	filename
	 700460	  15160	 292184	1007804	  f60bc	git

After:
	[torvalds@woody git]$ size git
	   text	   data	    bss	    dec	    hex	filename
	 670540	  15160	 292184	 977884	  eebdc	git

so it saves almost 30k of text-space (it actually saves more than that
with the default -O2, but I don't think that's necessarily a very relevant
number from a "try to shrink git" standpoint).

It might conceivably have a performance impact, but none of this should be
_that_ performance critical. The real cost is not generally in the wrapper
anyway, but in the code it wraps (ie the cost of "xread()" is all in the
read itself, not in the trivial wrapping of it).

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 160 insertions, 0 deletions

diff --git a/wrapper.c b/wrapper.c
new file mode 100644
index 0000000000..4e04f7661b
--- /dev/null
+++ b/wrapper.c
@@ -0,0 +1,160 @@
+/*
+ * Various trivial helper wrappers around standard functions
+ */
+#include "cache.h"
+
+char *xstrdup(const char *str)
+{
+	char *ret = strdup(str);
+	if (!ret) {
+		release_pack_memory(strlen(str) + 1, -1);
+		ret = strdup(str);
+		if (!ret)
+			die("Out of memory, strdup failed");
+	}
+	return ret;
+}
+
+void *xmalloc(size_t size)
+{
+	void *ret = malloc(size);
+	if (!ret && !size)
+		ret = malloc(1);
+	if (!ret) {
+		release_pack_memory(size, -1);
+		ret = malloc(size);
+		if (!ret && !size)
+			ret = malloc(1);
+		if (!ret)
+			die("Out of memory, malloc failed");
+	}
+#ifdef XMALLOC_POISON
+	memset(ret, 0xA5, size);
+#endif
+	return ret;
+}
+
+/*
+ * xmemdupz() allocates (len + 1) bytes of memory, duplicates "len" bytes of
+ * "data" to the allocated memory, zero terminates the allocated memory,
+ * and returns a pointer to the allocated memory. If the allocation fails,
+ * the program dies.
+ */
+void *xmemdupz(const void *data, size_t len)
+{
+	char *p = xmalloc(len + 1);
+	memcpy(p, data, len);
+	p[len] = '\0';
+	return p;
+}
+
+char *xstrndup(const char *str, size_t len)
+{
+	char *p = memchr(str, '\0', len);
+	return xmemdupz(str, p ? p - str : len);
+}
+
+void *xrealloc(void *ptr, size_t size)
+{
+	void *ret = realloc(ptr, size);
+	if (!ret && !size)
+		ret = realloc(ptr, 1);
+	if (!ret) {
+		release_pack_memory(size, -1);
+		ret = realloc(ptr, size);
+		if (!ret && !size)
+			ret = realloc(ptr, 1);
+		if (!ret)
+			die("Out of memory, realloc failed");
+	}
+	return ret;
+}
+
+void *xcalloc(size_t nmemb, size_t size)
+{
+	void *ret = calloc(nmemb, size);
+	if (!ret && (!nmemb || !size))
+		ret = calloc(1, 1);
+	if (!ret) {
+		release_pack_memory(nmemb * size, -1);
+		ret = calloc(nmemb, size);
+		if (!ret && (!nmemb || !size))
+			ret = calloc(1, 1);
+		if (!ret)
+			die("Out of memory, calloc failed");
+	}
+	return ret;
+}
+
+void *xmmap(void *start, size_t length,
+	int prot, int flags, int fd, off_t offset)
+{
+	void *ret = mmap(start, length, prot, flags, fd, offset);
+	if (ret == MAP_FAILED) {
+		if (!length)
+			return NULL;
+		release_pack_memory(length, fd);
+		ret = mmap(start, length, prot, flags, fd, offset);
+		if (ret == MAP_FAILED)
+			die("Out of memory? mmap failed: %s", strerror(errno));
+	}
+	return ret;
+}
+
+/*
+ * xread() is the same a read(), but it automatically restarts read()
+ * operations with a recoverable error (EAGAIN and EINTR). xread()
+ * DOES NOT GUARANTEE that "len" bytes is read even if the data is available.
+ */
+ssize_t xread(int fd, void *buf, size_t len)
+{
+	ssize_t nr;
+	while (1) {
+		nr = read(fd, buf, len);
+		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
+			continue;
+		return nr;
+	}
+}
+
+/*
+ * xwrite() is the same a write(), but it automatically restarts write()
+ * operations with a recoverable error (EAGAIN and EINTR). xwrite() DOES NOT
+ * GUARANTEE that "len" bytes is written even if the operation is successful.
+ */
+ssize_t xwrite(int fd, const void *buf, size_t len)
+{
+	ssize_t nr;
+	while (1) {
+		nr = write(fd, buf, len);
+		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
+			continue;
+		return nr;
+	}
+}
+
+int xdup(int fd)
+{
+	int ret = dup(fd);
+	if (ret < 0)
+		die("dup failed: %s", strerror(errno));
+	return ret;
+}
+
+FILE *xfdopen(int fd, const char *mode)
+{
+	FILE *stream = fdopen(fd, mode);
+	if (stream == NULL)
+		die("Out of memory? fdopen failed: %s", strerror(errno));
+	return stream;
+}
+
+int xmkstemp(char *template)
+{
+	int fd;
+
+	fd = mkstemp(template);
+	if (fd < 0)
+		die("Unable to create temporary file: %s", strerror(errno));
+	return fd;
+}