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main.c: Use fstat(2) on move_file 

This allows to reuse the same file descriptor to both open(2) and
fstat(2) the file.
This commit is contained in:
Xavier Del Campo Romero 2024-02-19 23:04:50 +01:00
parent f6b84b765d
commit a578ad6537
Signed by: xavi
GPG Key ID: 84FF3612A9BF43F2
1 changed files with 30 additions and 24 deletions
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54
main.c
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@ -1057,23 +1057,23 @@ end:
static int move_file(const char *const old, const char *const new)
{
int ret = -1;
FILE *const f = fopen(old, "rb");
const int fd = open(new, O_WRONLY | O_CREAT, 0600);
const int fd_old = open(old, O_RDONLY),
fd_new = open(new, O_WRONLY | O_CREAT, 0600);
struct stat sb;
if (!f)
if (fd_old < 0)
{
fprintf(stderr, "%s: fopen(3): %s\n", __func__, strerror(errno));
fprintf(stderr, "%s: open(2) fd_old: %s\n", __func__, strerror(errno));
goto end;
}
else if (fd < 0)
else if (fd_new < 0)
{
fprintf(stderr, "%s: open(2): %s\n", __func__, strerror(errno));
goto end;
}
else if (stat(old, &sb))
else if (fstat(fd_old, &sb))
{
fprintf(stderr, "%s: stat(2): %s\n", __func__, strerror(errno));
fprintf(stderr, "%s: fstat(2): %s\n", __func__, strerror(errno));
goto end;
}
@ -1082,24 +1082,30 @@ static int move_file(const char *const old, const char *const new)
char buf[BUFSIZ];
const off_t left = sb.st_size - i;
const size_t rem = left > sizeof buf ? sizeof buf : left;
ssize_t w;
const ssize_t r = read(fd_old, buf, rem);
if (!fread(buf, rem, 1, f))
if (r < 0)
{
fprintf(stderr, "%s: fread(3) failed, feof=%d, ferror=%d\n",
__func__, feof(f), ferror(f));
fprintf(stderr, "%s: read(2): %s\n", __func__, strerror(errno));
goto end;
}
else if ((w = write(fd, buf, rem)) < 0)
size_t wrem = r;
const void *p = buf;
while (wrem)
{
fprintf(stderr, "%s: write(2): %s\n", __func__, strerror(errno));
goto end;
}
else if (w != rem)
{
fprintf(stderr, "%s: write(2): expected to write %zu bytes, "
"only %ju written\n", __func__, rem, (intmax_t)w);
goto end;
const ssize_t w = write(fd_new, p, wrem);
if (w < 0)
{
fprintf(stderr, "%s: write(2): %s\n",
__func__, strerror(errno));
goto end;
}
p = (const char *)p + w;
wrem -= w;
}
i += rem;
@ -1108,15 +1114,15 @@ static int move_file(const char *const old, const char *const new)
ret = 0;
end:
if (fd >= 0 && close(fd))
if (fd_old >= 0 && close(fd_old))
{
fprintf(stderr, "%s: close(2): %s\n", __func__, strerror(errno));
fprintf(stderr, "%s: close(2) fd_old: %s\n", __func__, strerror(errno));
ret = -1;
}
if (f && fclose(f))
if (fd_new >= 0 && close(fd_new))
{
fprintf(stderr, "%s: fclose(3): %s\n", __func__, strerror(errno));
fprintf(stderr, "%s: close(2) fd_new: %s\n", __func__, strerror(errno));
ret = -1;
}