xref: /dports/devel/util-linux/util-linux-2.36/lib/path.c

/*
 * Simple functions to access files. Paths can be globally prefixed to read
 * data from an alternative source (e.g. a /proc dump for regression tests).
 *
 * The paths is possible to format by printf-like way for functions with "f"
 * postfix in the name (e.g. readf, openf, ... ul_path_readf_u64()).
 *
 * The ul_path_read_* API is possible to use without path_cxt handler. In this
 * case is not possible to use global prefix and printf-like formatting.
 *
 * No copyright is claimed.  This code is in the public domain; do with
 * it what you wish.
 *
 * Written by Karel Zak <kzak@redhat.com> [February 2018]
 */
#include <stdarg.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
#include <inttypes.h>
#include <errno.h>

#include "c.h"
#include "fileutils.h"
#include "all-io.h"
#include "path.h"
#include "debug.h"
#include "strutils.h"

/*
 * Debug stuff (based on include/debug.h)
 */
static UL_DEBUG_DEFINE_MASK(ulpath);
UL_DEBUG_DEFINE_MASKNAMES(ulpath) = UL_DEBUG_EMPTY_MASKNAMES;

#define ULPATH_DEBUG_INIT	(1 << 1)
#define ULPATH_DEBUG_CXT	(1 << 2)

#define DBG(m, x)       __UL_DBG(ulpath, ULPATH_DEBUG_, m, x)
#define ON_DBG(m, x)    __UL_DBG_CALL(ulpath, ULPATH_DEBUG_, m, x)

#define UL_DEBUG_CURRENT_MASK	UL_DEBUG_MASK(ulpath)
#include "debugobj.h"

void ul_path_init_debug(void)
{
	if (ulpath_debug_mask)
		return;
	__UL_INIT_DEBUG_FROM_ENV(ulpath, ULPATH_DEBUG_, 0, ULPATH_DEBUG);
}

struct path_cxt *ul_new_path(const char *dir, ...)
{
	struct path_cxt *pc = calloc(1, sizeof(*pc));

	if (!pc)
		return NULL;

	DBG(CXT, ul_debugobj(pc, "alloc"));

	pc->refcount = 1;
	pc->dir_fd = -1;

	if (dir) {
		int rc;
		va_list ap;

		va_start(ap, dir);
		rc = vasprintf(&pc->dir_path, dir, ap);
		va_end(ap);

		if (rc < 0 || !pc->dir_path)
			goto fail;
	}
	return pc;
fail:
	ul_unref_path(pc);
	return NULL;
}

void ul_ref_path(struct path_cxt *pc)
{
	if (pc)
		pc->refcount++;
}

void ul_unref_path(struct path_cxt *pc)
{
	if (!pc)
		return;

	pc->refcount--;

	if (pc->refcount <= 0) {
		DBG(CXT, ul_debugobj(pc, "dealloc"));
		if (pc->dialect)
			pc->free_dialect(pc);
		ul_path_close_dirfd(pc);
		free(pc->dir_path);
		free(pc->prefix);
		free(pc);
	}
}

int ul_path_set_prefix(struct path_cxt *pc, const char *prefix)
{
	char *p = NULL;

	assert(pc->dir_fd < 0);

	if (prefix) {
		p = strdup(prefix);
		if (!p)
			return -ENOMEM;
	}

	free(pc->prefix);
	pc->prefix = p;
	DBG(CXT, ul_debugobj(pc, "new prefix: '%s'", p));
	return 0;
}

const char *ul_path_get_prefix(struct path_cxt *pc)
{
	return pc ? pc->prefix : NULL;
}

int ul_path_set_dir(struct path_cxt *pc, const char *dir)
{
	char *p = NULL;

	if (dir) {
		p = strdup(dir);
		if (!p)
			return -ENOMEM;
	}

	if (pc->dir_fd >= 0) {
		close(pc->dir_fd);
		pc->dir_fd = -1;
	}

	free(pc->dir_path);
	pc->dir_path = p;
	DBG(CXT, ul_debugobj(pc, "new dir: '%s'", p));
	return 0;
}

const char *ul_path_get_dir(struct path_cxt *pc)
{
	return pc ? pc->dir_path : NULL;
}

int ul_path_set_dialect(struct path_cxt *pc, void *data, void free_data(struct path_cxt *))
{
	pc->dialect = data;
	pc->free_dialect = free_data;
	DBG(CXT, ul_debugobj(pc, "(re)set dialect"));
	return 0;
}

void *ul_path_get_dialect(struct path_cxt *pc)
{
	return pc ? pc->dialect : NULL;
}

int ul_path_set_enoent_redirect(struct path_cxt *pc, int (*func)(struct path_cxt *, const char *, int *))
{
	pc->redirect_on_enoent = func;
	return 0;
}

static const char *get_absdir(struct path_cxt *pc)
{
	int rc;
	const char *dirpath;

	if (!pc->prefix)
		return pc->dir_path;

	dirpath = pc->dir_path;
	if (!dirpath)
		return pc->prefix;
	if (*dirpath == '/')
		dirpath++;

	rc = snprintf(pc->path_buffer, sizeof(pc->path_buffer), "%s/%s", pc->prefix, dirpath);
	if (rc < 0)
		return NULL;
	if ((size_t)rc >= sizeof(pc->path_buffer)) {
		errno = ENAMETOOLONG;
		return NULL;
	}

	return pc->path_buffer;
}

int ul_path_is_accessible(struct path_cxt *pc)
{
	const char *path;
	assert(pc);

	if (pc->dir_fd >= 0)
		return 1;

	path = get_absdir(pc);
	if (!path)
		return 0;
	return access(path, F_OK) == 0;
}

int ul_path_get_dirfd(struct path_cxt *pc)
{
	assert(pc);
	assert(pc->dir_path);

	if (pc->dir_fd < 0) {
		const char *path = get_absdir(pc);
		if (!path)
			return -errno;

		DBG(CXT, ul_debugobj(pc, "opening dir: '%s'", path));
		pc->dir_fd = open(path, O_RDONLY|O_CLOEXEC);
	}

	return pc->dir_fd;
}

/* Note that next ul_path_get_dirfd() will reopen the directory */
void ul_path_close_dirfd(struct path_cxt *pc)
{
	assert(pc);

	if (pc->dir_fd >= 0) {
		DBG(CXT, ul_debugobj(pc, "closing dir"));
		close(pc->dir_fd);
		pc->dir_fd = -1;
	}
}

int ul_path_isopen_dirfd(struct path_cxt *pc)
{
	return pc && pc->dir_fd >= 0;
}

static const char *ul_path_mkpath(struct path_cxt *pc, const char *path, va_list ap)
{
	int rc;

	errno = 0;

	rc = vsnprintf(pc->path_buffer, sizeof(pc->path_buffer), path, ap);
	if (rc < 0) {
		if (!errno)
			errno = EINVAL;
		return NULL;
	}

	if ((size_t)rc >= sizeof(pc->path_buffer)) {
		errno = ENAMETOOLONG;
		return NULL;
	}

	return pc->path_buffer;
}

char *ul_path_get_abspath(struct path_cxt *pc, char *buf, size_t bufsz, const char *path, ...)
{
	if (path) {
		int rc;
		va_list ap;
		const char *tail = NULL, *dirpath = pc->dir_path;

		va_start(ap, path);
		tail = ul_path_mkpath(pc, path, ap);
		va_end(ap);

		if (dirpath && *dirpath == '/')
			dirpath++;
		if (tail && *tail == '/')
			tail++;

		rc = snprintf(buf, bufsz, "%s/%s/%s",
				pc->prefix ? pc->prefix : "",
				dirpath ? dirpath : "",
				tail ? tail : "");

		if ((size_t)rc >= bufsz) {
			errno = ENAMETOOLONG;
			return NULL;
		}
	} else {
		const char *tmp = get_absdir(pc);

		if (!tmp)
			return NULL;
		xstrncpy(buf, tmp, bufsz);
	}

	return buf;
}


int ul_path_access(struct path_cxt *pc, int mode, const char *path)
{
	int rc;

	if (!pc) {
		rc = access(path, mode);
		DBG(CXT, ul_debug("access '%s' [no context, rc=%d]", path, rc));
	} else {
		int dir = ul_path_get_dirfd(pc);
		if (dir < 0)
			return dir;
		if (*path == '/')
			path++;

		rc = faccessat(dir, path, mode, 0);

		if (rc && errno == ENOENT
		    && pc->redirect_on_enoent
		    && pc->redirect_on_enoent(pc, path, &dir) == 0)
			rc = faccessat(dir, path, mode, 0);

		DBG(CXT, ul_debugobj(pc, "access: '%s' [rc=%d]", path, rc));
	}
	return rc;
}

int ul_path_accessf(struct path_cxt *pc, int mode, const char *path, ...)
{
	va_list ap;
	const char *p;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_access(pc, mode, p);
}

int ul_path_stat(struct path_cxt *pc, struct stat *sb, const char *path)
{
	int rc;

	if (!pc) {
		rc = stat(path, sb);
		DBG(CXT, ul_debug("stat '%s' [no context, rc=%d]", path, rc));
	} else {
		int dir = ul_path_get_dirfd(pc);
		if (dir < 0)
			return dir;
		if (*path == '/')
			path++;

		rc = fstatat(dir, path, sb, 0);

		if (rc && errno == ENOENT
		    && pc->redirect_on_enoent
		    && pc->redirect_on_enoent(pc, path, &dir) == 0)
			rc = fstatat(dir, path, sb, 0);

		DBG(CXT, ul_debugobj(pc, "stat '%s' [rc=%d]", path, rc));
	}
	return rc;
}

int ul_path_open(struct path_cxt *pc, int flags, const char *path)
{
	int fd;

	if (!pc) {
		fd = open(path, flags);
		DBG(CXT, ul_debug("opening '%s' [no context]", path));
	} else {
		int fdx;
		int dir = ul_path_get_dirfd(pc);
		if (dir < 0)
			return dir;

		if (*path == '/')
			path++;

		fdx = fd = openat(dir, path, flags);

		if (fd < 0 && errno == ENOENT
		    && pc->redirect_on_enoent
		    && pc->redirect_on_enoent(pc, path, &dir) == 0)
			fd = openat(dir, path, flags);

		DBG(CXT, ul_debugobj(pc, "opening '%s'%s", path, fdx != fd ? " [redirected]" : ""));
	}
	return fd;
}

int ul_path_vopenf(struct path_cxt *pc, int flags, const char *path, va_list ap)
{
	const char *p = ul_path_mkpath(pc, path, ap);

	return !p ? -errno : ul_path_open(pc, flags, p);
}

int ul_path_openf(struct path_cxt *pc, int flags, const char *path, ...)
{
	va_list ap;
	int rc;

	va_start(ap, path);
	rc = ul_path_vopenf(pc, flags, path, ap);
	va_end(ap);

	return rc;
}

/*
 * Maybe stupid, but good enough ;-)
 */
static int mode2flags(const char *mode)
{
	int flags = 0;
	const char *p;

	for (p = mode; p && *p; p++) {
		if (*p == 'r' && *(p + 1) == '+')
			flags |= O_RDWR;
		else if (*p == 'r')
			flags |= O_RDONLY;

		else if (*p == 'w' && *(p + 1) == '+')
			flags |= O_RDWR | O_TRUNC;
		else if (*p == 'w')
			flags |= O_WRONLY | O_TRUNC;

		else if (*p == 'a' && *(p + 1) == '+')
			flags |= O_RDWR | O_APPEND;
		else if (*p == 'a')
			flags |= O_WRONLY | O_APPEND;
#ifdef O_CLOEXEC
		else if (*p == *UL_CLOEXECSTR)
			flags |= O_CLOEXEC;
#endif
	}

	return flags;
}

FILE *ul_path_fopen(struct path_cxt *pc, const char *mode, const char *path)
{
	int flags = mode2flags(mode);
	int fd = ul_path_open(pc, flags, path);

	if (fd < 0)
		return NULL;

	return fdopen(fd, mode);
}


FILE *ul_path_vfopenf(struct path_cxt *pc, const char *mode, const char *path, va_list ap)
{
	const char *p = ul_path_mkpath(pc, path, ap);

	return !p ? NULL : ul_path_fopen(pc, mode, p);
}

FILE *ul_path_fopenf(struct path_cxt *pc, const char *mode, const char *path, ...)
{
	FILE *f;
	va_list ap;

	va_start(ap, path);
	f = ul_path_vfopenf(pc, mode, path, ap);
	va_end(ap);

	return f;
}

/*
 * Open directory @path in read-onl mode. If the path is NULL then duplicate FD
 * to the directory addressed by @pc.
 */
DIR *ul_path_opendir(struct path_cxt *pc, const char *path)
{
	DIR *dir;
	int fd = -1;

	if (path)
		fd = ul_path_open(pc, O_RDONLY|O_CLOEXEC, path);
	else if (pc->dir_path) {
		int dirfd;

		DBG(CXT, ul_debugobj(pc, "duplicate dir path"));
		dirfd = ul_path_get_dirfd(pc);
		if (dirfd >= 0)
			fd = dup_fd_cloexec(dirfd, STDERR_FILENO + 1);
	}

	if (fd < 0)
		return NULL;

	dir = fdopendir(fd);
	if (!dir) {
		close(fd);
		return NULL;
	}
	if (!path)
		 rewinddir(dir);
	return dir;
}


/*
 * Open directory @path in read-onl mode. If the path is NULL then duplicate FD
 * to the directory addressed by @pc.
 */
DIR *ul_path_vopendirf(struct path_cxt *pc, const char *path, va_list ap)
{
	const char *p = ul_path_mkpath(pc, path, ap);

	return !p ? NULL : ul_path_opendir(pc, p);
}

/*
 * Open directory @path in read-onl mode. If the path is NULL then duplicate FD
 * to the directory addressed by @pc.
 */
DIR *ul_path_opendirf(struct path_cxt *pc, const char *path, ...)
{
	va_list ap;
	DIR *dir;

	va_start(ap, path);
	dir = ul_path_vopendirf(pc, path, ap);
	va_end(ap);

	return dir;
}

/*
 * If @path is NULL then readlink is called on @pc directory.
 */
ssize_t ul_path_readlink(struct path_cxt *pc, char *buf, size_t bufsiz, const char *path)
{
	int dirfd;

	if (!path) {
		const char *p = get_absdir(pc);
		if (!p)
			return -errno;
		return readlink(p, buf, bufsiz);
	}

	dirfd = ul_path_get_dirfd(pc);
	if (dirfd < 0)
		return dirfd;

	if (*path == '/')
		path++;

	return readlinkat(dirfd, path, buf, bufsiz);
}

/*
 * If @path is NULL then readlink is called on @pc directory.
 */
ssize_t ul_path_readlinkf(struct path_cxt *pc, char *buf, size_t bufsiz, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_readlink(pc, buf, bufsiz, p);
}

int ul_path_read(struct path_cxt *pc, char *buf, size_t len, const char *path)
{
	int rc, errsv;
	int fd;

	fd = ul_path_open(pc, O_RDONLY|O_CLOEXEC, path);
	if (fd < 0)
		return -errno;

	DBG(CXT, ul_debug(" reading '%s'", path));
	rc = read_all(fd, buf, len);

	errsv = errno;
	close(fd);
	errno = errsv;
	return rc;
}

int ul_path_vreadf(struct path_cxt *pc, char *buf, size_t len, const char *path, va_list ap)
{
	const char *p = ul_path_mkpath(pc, path, ap);

	return !p ? -errno : ul_path_read(pc, buf, len, p);
}

int ul_path_readf(struct path_cxt *pc, char *buf, size_t len, const char *path, ...)
{
	va_list ap;
	int rc;

	va_start(ap, path);
	rc = ul_path_vreadf(pc, buf, len, path, ap);
	va_end(ap);

	return rc;
}


/*
 * Returns newly allocated buffer with data from file. Maximal size is BUFSIZ
 * (send patch if you need something bigger;-)
 *
 * Returns size of the string!
 */
int ul_path_read_string(struct path_cxt *pc, char **str, const char *path)
{
	char buf[BUFSIZ];
	int rc;

	if (!str)
		return -EINVAL;

	*str = NULL;
	rc = ul_path_read(pc, buf, sizeof(buf) - 1, path);
	if (rc < 0)
		return rc;

	/* Remove tailing newline (usual in sysfs) */
	if (rc > 0 && *(buf + rc - 1) == '\n')
		--rc;

	buf[rc] = '\0';
	*str = strdup(buf);
	if (!*str)
		rc = -ENOMEM;

	return rc;
}

int ul_path_readf_string(struct path_cxt *pc, char **str, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_string(pc, str, p);
}

int ul_path_read_buffer(struct path_cxt *pc, char *buf, size_t bufsz, const char *path)
{
	int rc = ul_path_read(pc, buf, bufsz - 1, path);
	if (rc < 0)
		return rc;

	/* Remove tailing newline (usual in sysfs) */
	if (rc > 0 && *(buf + rc - 1) == '\n')
		buf[--rc] = '\0';
	else
		buf[rc - 1] = '\0';

	return rc;
}

int ul_path_readf_buffer(struct path_cxt *pc, char *buf, size_t bufsz, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_buffer(pc, buf, bufsz, p);
}

int ul_path_scanf(struct path_cxt *pc, const char *path, const char *fmt, ...)
{
	FILE *f;
	va_list fmt_ap;
	int rc;

	f = ul_path_fopen(pc, "r" UL_CLOEXECSTR, path);
	if (!f)
		return -EINVAL;

	DBG(CXT, ul_debug(" fscanf [%s] '%s'", fmt, path));

	va_start(fmt_ap, fmt);
	rc = vfscanf(f, fmt, fmt_ap);
	va_end(fmt_ap);

	fclose(f);
	return rc;
}

int ul_path_scanff(struct path_cxt *pc, const char *path, va_list ap, const char *fmt, ...)
{
	FILE *f;
	va_list fmt_ap;
	int rc;

	f = ul_path_vfopenf(pc, "r" UL_CLOEXECSTR, path, ap);
	if (!f)
		return -EINVAL;

	va_start(fmt_ap, fmt);
	rc = vfscanf(f, fmt, fmt_ap);
	va_end(fmt_ap);

	fclose(f);
	return rc;
}


int ul_path_read_s64(struct path_cxt *pc, int64_t *res, const char *path)
{
	int64_t x = 0;
	int rc;

	rc = ul_path_scanf(pc, path, "%"SCNd64, &x);
	if (rc != 1)
		return -1;
	if (res)
		*res = x;
	return 0;
}

int ul_path_readf_s64(struct path_cxt *pc, int64_t *res, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_s64(pc, res, p);
}

int ul_path_read_u64(struct path_cxt *pc, uint64_t *res, const char *path)
{
	uint64_t x = 0;
	int rc;

	rc = ul_path_scanf(pc, path, "%"SCNu64, &x);
	if (rc != 1)
		return -1;
	if (res)
		*res = x;
	return 0;
}

int ul_path_readf_u64(struct path_cxt *pc, uint64_t *res, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_u64(pc, res, p);
}

int ul_path_read_s32(struct path_cxt *pc, int *res, const char *path)
{
	int rc, x = 0;

	rc = ul_path_scanf(pc, path, "%d", &x);
	if (rc != 1)
		return -1;
	if (res)
		*res = x;
	return 0;
}

int ul_path_readf_s32(struct path_cxt *pc, int *res, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_s32(pc, res, p);
}

int ul_path_read_u32(struct path_cxt *pc, unsigned int *res, const char *path)
{
	int rc;
	unsigned int x;

	rc = ul_path_scanf(pc, path, "%u", &x);
	if (rc != 1)
		return -1;
	if (res)
		*res = x;
	return 0;
}

int ul_path_readf_u32(struct path_cxt *pc, unsigned int *res, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_u32(pc, res, p);
}

int ul_path_read_majmin(struct path_cxt *pc, dev_t *res, const char *path)
{
	int rc, maj, min;

	rc = ul_path_scanf(pc, path, "%d:%d", &maj, &min);
	if (rc != 2)
		return -1;
	if (res)
		*res = makedev(maj, min);
	return 0;
}

int ul_path_readf_majmin(struct path_cxt *pc, dev_t *res, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_read_majmin(pc, res, p);
}

int ul_path_write_string(struct path_cxt *pc, const char *str, const char *path)
{
	int rc, errsv;
	int fd;

	fd = ul_path_open(pc, O_WRONLY|O_CLOEXEC, path);
	if (fd < 0)
		return -errno;

	rc = write_all(fd, str, strlen(str));

	errsv = errno;
	close(fd);
	errno = errsv;
	return rc;
}

int ul_path_writef_string(struct path_cxt *pc, const char *str, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_write_string(pc, str, p);
}

int ul_path_write_s64(struct path_cxt *pc, int64_t num, const char *path)
{
	char buf[sizeof(stringify_value(LLONG_MAX))];
	int rc, errsv;
	int fd, len;

	fd = ul_path_open(pc, O_WRONLY|O_CLOEXEC, path);
	if (fd < 0)
		return -errno;

	len = snprintf(buf, sizeof(buf), "%" PRId64, num);
	if (len < 0 || (size_t) len >= sizeof(buf))
		rc = len < 0 ? -errno : -E2BIG;
	else
		rc = write_all(fd, buf, len);

	errsv = errno;
	close(fd);
	errno = errsv;
	return rc;
}

int ul_path_write_u64(struct path_cxt *pc, uint64_t num, const char *path)
{
	char buf[sizeof(stringify_value(ULLONG_MAX))];
	int rc, errsv;
	int fd, len;

	fd = ul_path_open(pc, O_WRONLY|O_CLOEXEC, path);
	if (fd < 0)
		return -errno;

	len = snprintf(buf, sizeof(buf), "%" PRIu64, num);
	if (len < 0 || (size_t) len >= sizeof(buf))
		rc = len < 0 ? -errno : -E2BIG;
	else
		rc = write_all(fd, buf, len);

	errsv = errno;
	close(fd);
	errno = errsv;
	return rc;
}

int ul_path_writef_u64(struct path_cxt *pc, uint64_t num, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_write_u64(pc, num, p);

}

int ul_path_count_dirents(struct path_cxt *pc, const char *path)
{
	DIR *dir;
	int r = 0;

	dir = ul_path_opendir(pc, path);
	if (!dir)
		return 0;

	while (xreaddir(dir)) r++;

	closedir(dir);
	return r;
}

int ul_path_countf_dirents(struct path_cxt *pc, const char *path, ...)
{
	const char *p;
	va_list ap;

	va_start(ap, path);
	p = ul_path_mkpath(pc, path, ap);
	va_end(ap);

	return !p ? -errno : ul_path_count_dirents(pc, p);
}

/*
 * Like fopen() but, @path is always prefixed by @prefix. This function is
 * useful in case when ul_path_* API is overkill.
 */
FILE *ul_prefix_fopen(const char *prefix, const char *path, const char *mode)
{
	char buf[PATH_MAX];

	if (!path)
		return NULL;
	if (!prefix)
		return fopen(path, mode);
	if (*path == '/')
		path++;

	snprintf(buf, sizeof(buf), "%s/%s", prefix, path);
	return fopen(buf, mode);
}

#ifdef HAVE_CPU_SET_T
static int ul_path_cpuparse(struct path_cxt *pc, cpu_set_t **set, int maxcpus, int islist, const char *path, va_list ap)
{
	FILE *f;
	size_t setsize, len = maxcpus * 7;
	char buf[len];
	int rc;

	*set = NULL;

	f = ul_path_vfopenf(pc, "r" UL_CLOEXECSTR, path, ap);
	if (!f)
		return -errno;

	rc = fgets(buf, len, f) == NULL ? -errno : 0;
	fclose(f);

	if (rc)
		return rc;

	len = strlen(buf);
	if (buf[len - 1] == '\n')
		buf[len - 1] = '\0';

	*set = cpuset_alloc(maxcpus, &setsize, NULL);
	if (!*set)
		return -ENOMEM;

	if (islist) {
		if (cpulist_parse(buf, *set, setsize, 0)) {
			cpuset_free(*set);
			return -EINVAL;
		}
	} else {
		if (cpumask_parse(buf, *set, setsize)) {
			cpuset_free(*set);
			return -EINVAL;
		}
	}
	return 0;
}

int ul_path_readf_cpuset(struct path_cxt *pc, cpu_set_t **set, int maxcpus, const char *path, ...)
{
	va_list ap;
	int rc = 0;

	va_start(ap, path);
	rc = ul_path_cpuparse(pc, set, maxcpus, 0, path, ap);
	va_end(ap);

	return rc;
}

int ul_path_readf_cpulist(struct path_cxt *pc, cpu_set_t **set, int maxcpus, const char *path, ...)
{
	va_list ap;
	int rc = 0;

	va_start(ap, path);
	rc = ul_path_cpuparse(pc, set, maxcpus, 1, path, ap);
	va_end(ap);

	return rc;
}

#endif /* HAVE_CPU_SET_T */


#ifdef TEST_PROGRAM_PATH
#include <getopt.h>

static void __attribute__((__noreturn__)) usage(void)
{
	fprintf(stdout, " %s [options] <dir> <command>\n\n", program_invocation_short_name);
	fputs(" -p, --prefix <dir>      redirect hardcoded paths to <dir>\n", stdout);

	fputs(" Commands:\n", stdout);
	fputs(" read-u64 <file>            read uint64_t from file\n", stdout);
	fputs(" read-s64 <file>            read  int64_t from file\n", stdout);
	fputs(" read-u32 <file>            read uint32_t from file\n", stdout);
	fputs(" read-s32 <file>            read  int32_t from file\n", stdout);
	fputs(" read-string <file>         read string  from file\n", stdout);
	fputs(" read-majmin <file>         read devno from file\n", stdout);
	fputs(" read-link <file>           read symlink\n", stdout);
	fputs(" write-string <file> <str>  write string from file\n", stdout);
	fputs(" write-u64 <file> <str>     write uint64_t from file\n", stdout);

	exit(EXIT_SUCCESS);
}

int main(int argc, char *argv[])
{
	int c;
	const char *prefix = NULL, *dir, *file, *command;
	struct path_cxt *pc = NULL;

	static const struct option longopts[] = {
		{ "prefix",	1, NULL, 'p' },
		{ "help",       0, NULL, 'h' },
		{ NULL, 0, NULL, 0 },
	};

	while((c = getopt_long(argc, argv, "p:h", longopts, NULL)) != -1) {
		switch(c) {
		case 'p':
			prefix = optarg;
			break;
		case 'h':
			usage();
			break;
		default:
			err(EXIT_FAILURE, "try --help");
		}
	}

	if (optind == argc)
		errx(EXIT_FAILURE, "<dir> not defined");
	dir = argv[optind++];

	ul_path_init_debug();

	pc = ul_new_path(dir);
	if (!pc)
		err(EXIT_FAILURE, "failed to initialize path context");
	if (prefix)
		ul_path_set_prefix(pc, prefix);

	if (optind == argc)
		errx(EXIT_FAILURE, "<command> not defined");
	command = argv[optind++];

	if (strcmp(command, "read-u32") == 0) {
		uint32_t res;

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_read_u32(pc, &res, file) != 0)
			err(EXIT_FAILURE, "read u64 failed");
		printf("read:  %s: %u\n", file, res);

		if (ul_path_readf_u32(pc, &res, "%s", file) != 0)
			err(EXIT_FAILURE, "readf u64 failed");
		printf("readf: %s: %u\n", file, res);

	} else if (strcmp(command, "read-s32") == 0) {
		int32_t res;

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_read_s32(pc, &res, file) != 0)
			err(EXIT_FAILURE, "read u64 failed");
		printf("read:  %s: %d\n", file, res);

		if (ul_path_readf_s32(pc, &res, "%s", file) != 0)
			err(EXIT_FAILURE, "readf u64 failed");
		printf("readf: %s: %d\n", file, res);

	} else if (strcmp(command, "read-u64") == 0) {
		uint64_t res;

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_read_u64(pc, &res, file) != 0)
			err(EXIT_FAILURE, "read u64 failed");
		printf("read:  %s: %" PRIu64 "\n", file, res);

		if (ul_path_readf_u64(pc, &res, "%s", file) != 0)
			err(EXIT_FAILURE, "readf u64 failed");
		printf("readf: %s: %" PRIu64 "\n", file, res);

	} else if (strcmp(command, "read-s64") == 0) {
		int64_t res;

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_read_s64(pc, &res, file) != 0)
			err(EXIT_FAILURE, "read u64 failed");
		printf("read:  %s: %" PRIu64 "\n", file, res);

		if (ul_path_readf_s64(pc, &res, "%s", file) != 0)
			err(EXIT_FAILURE, "readf u64 failed");
		printf("readf: %s: %" PRIu64 "\n", file, res);

	} else if (strcmp(command, "read-majmin") == 0) {
		dev_t res;

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_read_majmin(pc, &res, file) != 0)
			err(EXIT_FAILURE, "read maj:min failed");
		printf("read:  %s: %d\n", file, (int) res);

		if (ul_path_readf_majmin(pc, &res, "%s", file) != 0)
			err(EXIT_FAILURE, "readf maj:min failed");
		printf("readf: %s: %d\n", file, (int) res);

	} else if (strcmp(command, "read-string") == 0) {
		char *res;

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_read_string(pc, &res, file) < 0)
			err(EXIT_FAILURE, "read string failed");
		printf("read:  %s: %s\n", file, res);

		if (ul_path_readf_string(pc, &res, "%s", file) < 0)
			err(EXIT_FAILURE, "readf string failed");
		printf("readf: %s: %s\n", file, res);

	} else if (strcmp(command, "read-link") == 0) {
		char res[PATH_MAX];

		if (optind == argc)
			errx(EXIT_FAILURE, "<file> not defined");
		file = argv[optind++];

		if (ul_path_readlink(pc, res, sizeof(res), file) < 0)
			err(EXIT_FAILURE, "read symlink failed");
		printf("read:  %s: %s\n", file, res);

		if (ul_path_readlinkf(pc, res, sizeof(res), "%s", file) < 0)
			err(EXIT_FAILURE, "readf symlink failed");
		printf("readf: %s: %s\n", file, res);

	} else if (strcmp(command, "write-string") == 0) {
		char *str;

		if (optind + 1 == argc)
			errx(EXIT_FAILURE, "<file> <string> not defined");
		file = argv[optind++];
		str = argv[optind++];

		if (ul_path_write_string(pc, str, file) != 0)
			err(EXIT_FAILURE, "write string failed");
		if (ul_path_writef_string(pc, str, "%s", file) != 0)
			err(EXIT_FAILURE, "writef string failed");

	} else if (strcmp(command, "write-u64") == 0) {
		uint64_t num;

		if (optind + 1 == argc)
			errx(EXIT_FAILURE, "<file> <num> not defined");
		file = argv[optind++];
		num = strtoumax(argv[optind++], NULL, 0);

		if (ul_path_write_u64(pc, num, file) != 0)
			err(EXIT_FAILURE, "write u64 failed");
		if (ul_path_writef_u64(pc, num, "%s", file) != 0)
			err(EXIT_FAILURE, "writef u64 failed");
	}

	ul_unref_path(pc);
	return EXIT_SUCCESS;
}
#endif /* TEST_PROGRAM_PATH */