feat(dirent): directory iteration

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2026-09-05 21:08:57 -04:00
parent a2f7c33601
commit 5af4197ee9
14 changed files with 1139 additions and 0 deletions
+423
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@@ -0,0 +1,423 @@
/*
* vlibc — dirent test (todo 24).
*
* Exercises the dirent.h surface end to end against a scratch directory
* created with raw syscalls:
*
* 1. opendir on the temp dir lists exactly . .. alpha beta gamma; every
* entry carries a nonzero d_ino; . reports d_type DT_DIR and alpha
* DT_REG.
* 2. readdir past the end returns NULL; a repeated readdir stays NULL.
* 3. rewinddir re-lists the same five entries.
* 4. dirfd returns a usable descriptor; fdopendir succeeds on a raw
* directory descriptor.
* 5. Level 2: scandir + alphasort return the five entries sorted
* (. .. alpha beta gamma), NULL-terminated, with d_type copied, and
* the caller can free() every element and the array.
*
* The -f mode covers the failure paths, all asserted on return values
* only: opendir of a nonexistent directory returns NULL, fdopendir of a
* regular-file descriptor returns NULL, and a seekdir back to a saved
* telldir location resumes at the entry that originally followed it. The
* library writes errno on these paths, so -f exits through raw
* SYS_exit_group (house pattern); the default mode never triggers an
* errno-writing library path.
*
* All diagnostics go through raw SYS_write (no stdio); the test reads no
* host headers — under -Iinclude the vlibc public headers shadow GCC's
* internal ones. Not part of the library proper; compiled manually for
* this todo (the tests/ + make check wiring is owned by a later todo).
*/
#include <dirent.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include "../src/internal/syscall.h"
#define DIRPATH "/tmp/vlibc-t24"
static const char *const FILES[3] = {
DIRPATH "/alpha",
DIRPATH "/beta",
DIRPATH "/gamma",
};
static int failures;
/* Write a NUL-terminated string to fd via the raw syscall layer. The
* optimize attribute keeps GCC from lowering the length loop into a
* strlen call, which would leave a vlibc-owned symbol undefined in this
* host-linked standalone binary (house idiom, see src/string). */
static __attribute__((optimize("no-tree-loop-distribute-patterns"))) void
say(int fd, const char *s)
{
long n = 0;
while (s[n] != '\0')
{
n++;
}
__syscall3(SYS_write, fd, (long)s, n);
}
/* Write v in decimal to fd. */
static void
say_dec(int fd, unsigned long v) // NOLINT(bugprone-easily-swappable-parameters)
{
char buf[24];
int i = (int)sizeof(buf);
buf[--i] = '\0';
do
{
buf[--i] = (char)('0' + (v % 10));
v /= 10;
} while (v != 0);
__syscall3(SYS_write, fd, (long)(buf + i), (long)(sizeof(buf) - 1 - i));
}
static void
check(int cond, const char *what)
{
if (cond)
{
say(1, "PASS: ");
say(1, what);
say(1, "\n");
}
else
{
say(2, "FAIL: ");
say(2, what);
say(2, "\n");
failures++;
}
}
/* Drop any leftover scratch dir (files, then the dir itself); errors are
* fine when nothing exists yet. */
static void
rm_tree(void)
{
int i;
for (i = 0; i < 3; i++)
{
__syscall3(SYS_unlinkat, AT_FDCWD, (long)FILES[i], 0);
}
__syscall3(SYS_unlinkat, AT_FDCWD, (long)DIRPATH, AT_REMOVEDIR);
}
/* Create the scratch directory and its three one-byte files. */
static int
make_dir(void)
{
int fd;
int i;
rm_tree();
if ((int)__syscall3(SYS_mkdirat, AT_FDCWD, (long)DIRPATH, 0700) != 0)
{
return -1;
}
for (i = 0; i < 3; i++)
{
fd = (int)__syscall4(SYS_openat, AT_FDCWD, (long)FILES[i],
O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (fd < 0)
{
return -1;
}
__syscall3(SYS_write, fd, (long)"x", 1);
__syscall1(SYS_close, fd);
}
return 0;
}
/* A full listing captured as copied names. */
struct listing
{
char names[8][64];
int count;
};
/* Drain dir, copying each entry name into ls. */
static void
fill_listing(DIR *d, struct listing *ls)
{
struct dirent *e;
int n = 0;
while ((e = readdir(d)) != NULL)
{
if (n < 8)
{
strcpy(ls->names[n], e->d_name);
}
n++;
}
ls->count = n;
}
static int
has_name(const struct listing *ls, const char *name)
{
int i;
for (i = 0; i < ls->count; i++)
{
if (strcmp(ls->names[i], name) == 0)
{
return 1;
}
}
return 0;
}
static int
same_sets(const struct listing *x, const struct listing *y)
{
int i;
if (x->count != y->count)
{
return 0;
}
for (i = 0; i < x->count; i++)
{
if (!has_name(y, x->names[i]))
{
return 0;
}
}
return 1;
}
/* Scenarios 1-4: iteration, exhaustion, rewind, dirfd/fdopendir. */
static void
basic_scenarios(void)
{
struct listing first;
struct listing second;
DIR *d;
struct dirent *e;
int n = 0;
d = opendir(DIRPATH);
check(d != NULL, "opendir on the temp directory succeeds");
if (d == NULL)
{
return;
}
check(dirfd(d) >= 0, "dirfd on the open stream returns a valid descriptor");
first.count = 0;
while ((e = readdir(d)) != NULL)
{
check(e->d_ino != 0, "every entry reports a nonzero d_ino");
if (strcmp(e->d_name, ".") == 0)
{
check(e->d_type == DT_DIR, "the . entry carries d_type DT_DIR");
}
if (strcmp(e->d_name, "alpha") == 0)
{
check(e->d_type == DT_REG, "the alpha file carries d_type DT_REG");
}
if (n < 8)
{
strcpy(first.names[n], e->d_name);
}
n++;
}
first.count = n;
check(first.count == 5, "the first pass lists exactly 5 entries");
check(readdir(d) == NULL, "readdir at end of directory returns NULL");
check(readdir(d) == NULL, "a further readdir at end still returns NULL");
check(has_name(&first, ".") && has_name(&first, "..") &&
has_name(&first, "alpha") && has_name(&first, "beta") &&
has_name(&first, "gamma"),
"the first pass sees . .. alpha beta gamma");
rewinddir(d);
fill_listing(d, &second);
check(second.count == 5, "after rewinddir the second pass lists 5 entries again");
check(same_sets(&first, &second), "the rewound listing matches the first listing");
check(closedir(d) == 0, "closedir returns 0");
{
int fd = (int)__syscall3(SYS_openat, AT_FDCWD, (long)DIRPATH,
O_RDONLY | O_DIRECTORY);
DIR *dd;
check(fd >= 0, "raw open of the directory succeeds");
if (fd < 0)
{
return;
}
dd = fdopendir(fd);
check(dd != NULL, "fdopendir on a directory descriptor succeeds");
if (dd != NULL)
{
check(closedir(dd) == 0, "closedir after fdopendir returns 0");
}
else
{
__syscall1(SYS_close, fd);
}
}
}
#if VLIBC_LEVEL_GE(2)
/* Scenario 5 (level 2): scandir + alphasort. */
static void
scandir_scenario(void)
{
struct dirent **names = NULL;
int n;
int i;
n = scandir(DIRPATH, &names, NULL, alphasort);
check(n == 5, "scandir returns the 5 entries");
if (names == NULL)
{
return;
}
check(names[n] == NULL, "the scandir array is NULL-terminated");
check(strcmp(names[0]->d_name, ".") == 0 && strcmp(names[1]->d_name, "..") == 0,
"alphasort puts . and .. first in that order");
check(strcmp(names[2]->d_name, "alpha") == 0 &&
strcmp(names[3]->d_name, "beta") == 0 &&
strcmp(names[4]->d_name, "gamma") == 0,
"alphasort orders the files alpha beta gamma");
check(names[2]->d_type == DT_REG, "scandir copies d_type into its entries");
for (i = 0; i < n; i++)
{
free(names[i]);
}
free(names);
}
#endif /* VLIBC_LEVEL_GE(2) */
/*
* Failure scenarios (-f): every assertion is on the return value only.
* opendir/fdopendir write errno on these paths (host-TCB hazard), so the
* process exits through raw SYS_exit_group.
*/
static int
failure_scenarios(void)
{
struct dirent *e1;
struct dirent *e2;
struct dirent *e3;
int rc = 0;
int fdf;
long loc;
DIR *d;
if (make_dir() != 0)
{
say(2, "FAIL: cannot set up the temp directory\n");
return 1;
}
if (opendir("/nonexistent/vlibc-dir") != NULL)
{
say(2, "FAIL: opendir on a nonexistent directory did not return NULL\n");
rc = 1;
}
else
{
say(1, "PASS: opendir on a nonexistent directory -> NULL\n");
}
fdf = (int)__syscall3(SYS_openat, AT_FDCWD, (long)FILES[0], O_RDONLY);
if (fdf >= 0)
{
d = fdopendir(fdf);
if (d != NULL)
{
say(2, "FAIL: fdopendir on a regular-file descriptor did not return NULL\n");
rc = 1;
closedir(d);
}
else
{
say(1, "PASS: fdopendir on a regular-file descriptor -> NULL\n");
__syscall1(SYS_close, fdf);
}
}
d = opendir(DIRPATH);
if (d == NULL)
{
say(2, "FAIL: opendir failed for the seekdir round trip\n");
rc = 1;
}
else
{
e1 = readdir(d);
loc = telldir(d);
e2 = readdir(d);
if (e1 == NULL || e2 == NULL)
{
say(2, "FAIL: not enough entries for the seekdir round trip\n");
rc = 1;
}
else
{
seekdir(d, loc);
e3 = readdir(d);
if (e3 != NULL && strcmp(e3->d_name, e2->d_name) == 0)
{
say(1, "PASS: seekdir back to a telldir location resumes at the same entry\n");
}
else
{
say(2, "FAIL: seekdir did not resume at the telldir location\n");
rc = 1;
}
}
closedir(d);
}
rm_tree();
return rc;
}
int
main(int argc, char **argv)
{
if (argc == 2 && argv[1][0] == '-' && argv[1][1] == 'f')
{
int rc = failure_scenarios();
__syscall1(SYS_exit_group, rc);
return rc; /* not reached */
}
if (make_dir() != 0)
{
say(2, "FAIL: cannot set up the temp directory\n");
return 1;
}
basic_scenarios();
#if VLIBC_LEVEL_GE(2)
scandir_scenario();
#endif
rm_tree();
if (failures > 0)
{
say(2, "FAILED (");
say_dec(2, (unsigned long)failures);
say(2, " check(s))\n");
return 1;
}
say(1, "all dirent tests passed\n");
return 0;
}