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fileio: Add openat() like helpers

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This commit is contained in:
Daan De Meyer
2022-11-09 11:14:10 +01:00
parent 92dae2bd23
commit 0ab5e2a4b4
2 changed files with 42 additions and 24 deletions
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src/basic/fileio.c
+24 -21
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@@ -43,16 +43,17 @@
* can detect EOFs. */
#define READ_VIRTUAL_BYTES_MAX (4U*1024U*1024U - 2U)
int fopen_unlocked(const char *path, const char *options, FILE **ret) {
int fopen_unlocked_at(int dir_fd, const char *path, const char *options, int flags, FILE **ret) {
int r;
assert(ret);
FILE *f = fopen(path, options);
if (!f)
return -errno;
r = xfopenat(dir_fd, path, options, flags, ret);
if (r < 0)
return r;
(void) __fsetlocking(f, FSETLOCKING_BYCALLER);
(void) __fsetlocking(*ret, FSETLOCKING_BYCALLER);
*ret = f;
return 0;
}
@@ -209,7 +210,8 @@ int write_string_stream_ts(
return 0;
}
static int write_string_file_atomic(
static int write_string_file_atomic_at(
int dir_fd,
const char *fn,
const char *line,
WriteStringFileFlags flags,
@@ -225,7 +227,7 @@ static int write_string_file_atomic(
/* Note that we'd really like to use O_TMPFILE here, but can't really, since we want replacement
* semantics here, and O_TMPFILE can't offer that. i.e. rename() replaces but linkat() doesn't. */
r = fopen_temporary(fn, &f, &p);
r = fopen_temporary_at(dir_fd, fn, &f, &p);
if (r < 0)
return r;
@@ -237,7 +239,7 @@ static int write_string_file_atomic(
if (r < 0)
goto fail;
if (rename(p, fn) < 0) {
if (renameat(dir_fd, p, dir_fd, fn) < 0) {
r = -errno;
goto fail;
}
@@ -252,11 +254,12 @@ static int write_string_file_atomic(
return 0;
fail:
(void) unlink(p);
(void) unlinkat(dir_fd, p, 0);
return r;
}
int write_string_file_ts(
int write_string_file_ts_at(
int dir_fd,
const char *fn,
const char *line,
WriteStringFileFlags flags,
@@ -272,7 +275,7 @@ int write_string_file_ts(
assert(!((flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE) && (flags & WRITE_STRING_FILE_SYNC)));
if (flags & WRITE_STRING_FILE_MKDIR_0755) {
r = mkdir_parents(fn, 0755);
r = mkdirat_parents(dir_fd, fn, 0755);
if (r < 0)
return r;
}
@@ -280,7 +283,7 @@ int write_string_file_ts(
if (flags & WRITE_STRING_FILE_ATOMIC) {
assert(flags & WRITE_STRING_FILE_CREATE);
r = write_string_file_atomic(fn, line, flags, ts);
r = write_string_file_atomic_at(dir_fd, fn, line, flags, ts);
if (r < 0)
goto fail;
@@ -289,12 +292,12 @@ int write_string_file_ts(
assert(!ts);
/* We manually build our own version of fopen(..., "we") that works without O_CREAT and with O_NOFOLLOW if needed. */
fd = open(fn, O_CLOEXEC|O_NOCTTY |
(FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) |
(FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0) |
(FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0) |
(FLAGS_SET(flags, WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) ? O_RDWR : O_WRONLY),
(FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0666));
fd = openat(dir_fd, fn, O_CLOEXEC|O_NOCTTY |
(FLAGS_SET(flags, WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0) |
(FLAGS_SET(flags, WRITE_STRING_FILE_CREATE) ? O_CREAT : 0) |
(FLAGS_SET(flags, WRITE_STRING_FILE_TRUNCATE) ? O_TRUNC : 0) |
(FLAGS_SET(flags, WRITE_STRING_FILE_SUPPRESS_REDUNDANT_VIRTUAL) ? O_RDWR : O_WRONLY),
(FLAGS_SET(flags, WRITE_STRING_FILE_MODE_0600) ? 0600 : 0666));
if (fd < 0) {
r = -errno;
goto fail;
@@ -364,7 +367,7 @@ int read_one_line_file(const char *fn, char **line) {
return read_line(f, LONG_LINE_MAX, line);
}
int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
int verify_file_at(int dir_fd, const char *fn, const char *blob, bool accept_extra_nl) {
_cleanup_fclose_ FILE *f = NULL;
_cleanup_free_ char *buf = NULL;
size_t l, k;
@@ -382,7 +385,7 @@ int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
if (!buf)
return -ENOMEM;
r = fopen_unlocked(fn, "re", &f);
r = fopen_unlocked_at(dir_fd, fn, "re", 0, &f);
if (r < 0)
return r;