git/copy.c
Johannes Schindelin 584de0b4c2 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>
2024-04-19 12:38:19 +02:00

126 lines
2.7 KiB
C

#include "cache.h"
int copy_fd(int ifd, int ofd)
{
while (1) {
char buffer[8192];
ssize_t len = xread(ifd, buffer, sizeof(buffer));
if (!len)
break;
if (len < 0)
return COPY_READ_ERROR;
if (write_in_full(ofd, buffer, len) < 0)
return COPY_WRITE_ERROR;
}
return 0;
}
static int copy_times(const char *dst, const char *src)
{
struct stat st;
struct utimbuf times;
if (stat(src, &st) < 0)
return -1;
times.actime = st.st_atime;
times.modtime = st.st_mtime;
if (utime(dst, &times) < 0)
return -1;
return 0;
}
int copy_file(const char *dst, const char *src, int mode)
{
int fdi, fdo, status;
mode = (mode & 0111) ? 0777 : 0666;
if ((fdi = open(src, O_RDONLY)) < 0)
return fdi;
if ((fdo = open(dst, O_WRONLY | O_CREAT | O_EXCL, mode)) < 0) {
close(fdi);
return fdo;
}
status = copy_fd(fdi, fdo);
switch (status) {
case COPY_READ_ERROR:
error_errno("copy-fd: read returned");
break;
case COPY_WRITE_ERROR:
error_errno("copy-fd: write returned");
break;
}
close(fdi);
if (close(fdo) != 0)
return error_errno("%s: close error", dst);
if (!status && adjust_shared_perm(dst))
return -1;
return status;
}
int copy_file_with_time(const char *dst, const char *src, int mode)
{
int status = copy_file(dst, src, mode);
if (!status)
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;
}