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dirent-util: add FOREACH macro for iterating through getdents64() buffers

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We already have a similar loop twice, let's make it easier to read via
an iteration macro.

(The new macro is a bit more careful even, as it verifies the full
dirent fits into the remaining buffer when returning it)
This commit is contained in:
Lennart Poettering
2021-10-23 00:28:24 +02:00
parent ca664db258
commit a4e70ef7ba
3 changed files with 10 additions and 10 deletions
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5
src/basic/dirent-util.h
View File

@@ -51,3 +51,8 @@ assert_cc(offsetof(struct dirent, d_type) == offsetof(struct dirent64, d_type));
assert_cc(sizeof_field(struct dirent, d_type) == sizeof_field(struct dirent64, d_type));
assert_cc(offsetof(struct dirent, d_name) == offsetof(struct dirent64, d_name));
assert_cc(sizeof_field(struct dirent, d_name) == sizeof_field(struct dirent64, d_name));
#define FOREACH_DIRENT_IN_BUFFER(de, buf, sz) \
for (void *_end = (uint8_t*) ({ (de) = (buf); }) + (sz); \
(uint8_t*) (de) < (uint8_t*) _end; \
(de) = (struct dirent*) ((uint8_t*) (de) + (de)->d_reclen))

13
src/basic/recurse-dir.c
View File

@@ -30,6 +30,7 @@ int readdir_all(int dir_fd,
DirectoryEntries **ret) {
_cleanup_free_ DirectoryEntries *de = NULL;
struct dirent *entry;
DirectoryEntries *nde;
size_t add, sz, j;
@@ -53,7 +54,7 @@ int readdir_all(int dir_fd,
bs = MIN(MALLOC_SIZEOF_SAFE(de) - offsetof(DirectoryEntries, buffer), (size_t) SSIZE_MAX);
assert(bs > de->buffer_size);
n = getdents64(dir_fd, de->buffer + de->buffer_size, bs - de->buffer_size);
n = getdents64(dir_fd, (uint8_t*) de->buffer + de->buffer_size, bs - de->buffer_size);
if (n < 0)
return -errno;
if (n == 0)
@@ -77,10 +78,7 @@ int readdir_all(int dir_fd,
}
de->n_entries = 0;
for (struct dirent *entry = (struct dirent*) de->buffer;
(uint8_t*) entry < de->buffer + de->buffer_size;
entry = (struct dirent*) ((uint8_t*) entry + entry->d_reclen)) {
FOREACH_DIRENT_IN_BUFFER(entry, de->buffer, de->buffer_size) {
if (ignore_dirent(entry, flags))
continue;
@@ -100,10 +98,7 @@ int readdir_all(int dir_fd,
de->entries = (struct dirent**) ((uint8_t*) de + ALIGN(offsetof(DirectoryEntries, buffer) + de->buffer_size));
j = 0;
for (struct dirent *entry = (struct dirent*) de->buffer;
(uint8_t*) entry < de->buffer + de->buffer_size;
entry = (struct dirent*) ((uint8_t*) entry + entry->d_reclen)) {
FOREACH_DIRENT_IN_BUFFER(entry, de->buffer, de->buffer_size) {
if (ignore_dirent(entry, flags))
continue;

2
src/basic/recurse-dir.h
View File

@@ -71,7 +71,7 @@ typedef struct DirectoryEntries {
size_t n_entries;
struct dirent** entries;
size_t buffer_size;
uint8_t buffer[] _alignas_(struct dirent);
struct dirent buffer[];
} DirectoryEntries;
int readdir_all(int dir_fd, RecurseDirFlags flags, DirectoryEntries **ret);