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Add directory stream wrappers #40

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andrew merged 2 commits from 10 into main 2026-08-03 15:26:00 -04:00
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2 changed files with 31 additions and 1 deletions
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25
src/dir.c
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@@ -1,10 +1,20 @@
/* POSIX directory-stream wrappers. */
/*
* POSIX directory-stream wrappers.
*
* opendir(3), fdopendir(3), readdir(3), closedir(3), and rewinddir(3) expose
* three different failure conventions between them. These wrappers turn all
* three into error contexts and make end-of-directory an explicit AKERR_EOF.
*/
#include <akstdlib.h>
andrew marked this conversation as resolved
andrew commented 2026-08-03 14:02:55 -04:00
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None of these functions have man style comment blocks for context on their operations, the same way other sources in this library do.

None of these functions have `man` style comment blocks for context on their operations, the same way other sources in this library do.
#include <errno.h>
#include "aksl_internal.h"
/*
* opendir(3) returns NULL for failure. Clear *dest first so a failed open
* cannot leave the caller holding a stale directory stream.
*/
akerr_ErrorContext AKERR_NOIGNORE *aksl_opendir(const char *pathname, DIR **dest)
{
PREPARE_ERROR(e);
@@ -19,6 +29,10 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_opendir(const char *pathname, DIR **dest
SUCCEED_RETURN(e);
}
/*
* fdopendir(3) takes ownership of fd only when it succeeds. On success the
* matching aksl_closedir call closes both the stream and its descriptor.
*/
akerr_ErrorContext AKERR_NOIGNORE *aksl_fdopendir(int fd, DIR **dest)
{
PREPARE_ERROR(e);
@@ -30,6 +44,10 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_fdopendir(int fd, DIR **dest)
SUCCEED_RETURN(e);
}
/*
* readdir(3) owns and may reuse its returned storage. Copy the entry into the
* caller's destination, and use errno to distinguish failure from exhaustion.
*/
akerr_ErrorContext AKERR_NOIGNORE *aksl_readdir(DIR *dirp, struct dirent *dest)
{
struct dirent *entry = NULL;
@@ -50,6 +68,7 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_readdir(DIR *dirp, struct dirent *dest)
SUCCEED_RETURN(e);
}
/* closedir(3) reports its failure directly and invalidates dirp on success. */
akerr_ErrorContext AKERR_NOIGNORE *aksl_closedir(DIR *dirp)
{
PREPARE_ERROR(e);
@@ -60,6 +79,10 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_closedir(DIR *dirp)
SUCCEED_RETURN(e);
}
/*
* rewinddir(3) has no failure return. Preserve that contract after rejecting
* a NULL stream, which would otherwise be undefined behaviour.
*/
akerr_ErrorContext AKERR_NOIGNORE *aksl_rewinddir(DIR *dirp)
{
PREPARE_ERROR(e);

7
tests/test_dir.c
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@@ -23,14 +23,21 @@ static int test_open_errors_and_nulls(void)
DIR *dirp = (DIR *)1;
struct dirent entry;
/* opendir propagates missing-path and non-directory failures. */
AKSL_CHECK_STATUS(aksl_opendir("/nonexistent/aksl/dir", &dirp), ENOENT);
AKSL_CHECK(dirp == NULL);
AKSL_CHECK(aksl_temp_file(file, sizeof(file)) == 0);
AKSL_CHECK_STATUS(aksl_opendir(file, &dirp), ENOTDIR);
/* Every pointer required by the wrapped operation rejects NULL. */
AKSL_CHECK_STATUS(aksl_opendir(NULL, &dirp), AKERR_NULLPOINTER);
AKSL_CHECK_STATUS(aksl_opendir(".", NULL), AKERR_NULLPOINTER);
/* fdopendir propagates an invalid descriptor and validates its out-param. */
AKSL_CHECK_STATUS(aksl_fdopendir(-1, &dirp), EBADF);
AKSL_CHECK_STATUS(aksl_fdopendir(0, NULL), AKERR_NULLPOINTER);
/* The remaining wrappers reject NULL streams and destinations. */
AKSL_CHECK_STATUS(aksl_readdir(NULL, &entry), AKERR_NULLPOINTER);
AKSL_CHECK_OK(aksl_opendir(".", &dirp));
AKSL_CHECK_STATUS(aksl_readdir(dirp, NULL), AKERR_NULLPOINTER);