Add a helper function to compare file contents

In the next commit, Git will learn to disallow hooks during `git clone`
operations _except_ when those hooks come from the templates (which are
inherently supposed to be trusted). To that end, we add a function to
compare the contents of two files.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This commit is contained in:
Johannes Schindelin
2024-03-30 15:59:20 +01:00
parent df93e407f0
commit 584de0b4c2
4 changed files with 123 additions and 0 deletions

58
copy.c
View File

@@ -65,3 +65,61 @@ int copy_file_with_time(const char *dst, const char *src, int mode)
return copy_times(dst, src);
return status;
}
static int do_symlinks_match(const char *path1, const char *path2)
{
struct strbuf buf1 = STRBUF_INIT, buf2 = STRBUF_INIT;
int ret = 0;
if (!strbuf_readlink(&buf1, path1, 0) &&
!strbuf_readlink(&buf2, path2, 0))
ret = !strcmp(buf1.buf, buf2.buf);
strbuf_release(&buf1);
strbuf_release(&buf2);
return ret;
}
int do_files_match(const char *path1, const char *path2)
{
struct stat st1, st2;
int fd1 = -1, fd2 = -1, ret = 1;
char buf1[8192], buf2[8192];
if ((fd1 = open_nofollow(path1, O_RDONLY)) < 0 ||
fstat(fd1, &st1) || !S_ISREG(st1.st_mode)) {
if (fd1 < 0 && errno == ELOOP)
/* maybe this is a symbolic link? */
return do_symlinks_match(path1, path2);
ret = 0;
} else if ((fd2 = open_nofollow(path2, O_RDONLY)) < 0 ||
fstat(fd2, &st2) || !S_ISREG(st2.st_mode)) {
ret = 0;
}
if (ret)
/* to match, neither must be executable, or both */
ret = !(st1.st_mode & 0111) == !(st2.st_mode & 0111);
if (ret)
ret = st1.st_size == st2.st_size;
while (ret) {
ssize_t len1 = read_in_full(fd1, buf1, sizeof(buf1));
ssize_t len2 = read_in_full(fd2, buf2, sizeof(buf2));
if (len1 < 0 || len2 < 0 || len1 != len2)
ret = 0; /* read error or different file size */
else if (!len1) /* len2 is also 0; hit EOF on both */
break; /* ret is still true */
else
ret = !memcmp(buf1, buf2, len1);
}
if (fd1 >= 0)
close(fd1);
if (fd2 >= 0)
close(fd2);
return ret;
}