libbb/xfuncs_printf.c - busybox - Git at Google

 /* vi: set sw=4 ts=4: */
 /*
  * Utility routines.
  *
  * Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
  * Copyright (C) 2006 Rob Landley
  * Copyright (C) 2006 Denys Vlasenko
  *
  * Licensed under GPL version 2, see file LICENSE in this tarball for details.
  */

 /* We need to have separate xfuncs.c and xfuncs_printf.c because
  * with current linkers, even with section garbage collection,
  * if *.o module references any of XXXprintf functions, you pull in
  * entire printf machinery. Even if you do not use the function
  * which uses XXXprintf.
  *
  * xfuncs.c contains functions (not necessarily xfuncs)
  * which do not pull in printf, directly or indirectly.
  * xfunc_printf.c contains those which do.
  */

 #include "libbb.h"


 /* All the functions starting with "x" call bb_error_msg_and_die() if they
  * fail, so callers never need to check for errors.  If it returned, it
  * succeeded. */

 #ifndef DMALLOC
 /* dmalloc provides variants of these that do abort() on failure.
  * Since dmalloc's prototypes overwrite the impls here as they are
  * included after these prototypes in libbb.h, all is well.
  */
 // Warn if we can't allocate size bytes of memory.
 void* FAST_FUNC malloc_or_warn(size_t size)
 {
 	void *ptr = malloc(size);
 	if (ptr == NULL && size != 0)
 		bb_error_msg(bb_msg_memory_exhausted);
 	return ptr;
 }

 // Die if we can't allocate size bytes of memory.
 void* FAST_FUNC xmalloc(size_t size)
 {
 	void *ptr = malloc(size);
 	if (ptr == NULL && size != 0)
 		bb_error_msg_and_die(bb_msg_memory_exhausted);
 	return ptr;
 }

 // Die if we can't resize previously allocated memory.  (This returns a pointer
 // to the new memory, which may or may not be the same as the old memory.
 // It'll copy the contents to a new chunk and free the old one if necessary.)
 void* FAST_FUNC xrealloc(void *ptr, size_t size)
 {
 	ptr = realloc(ptr, size);
 	if (ptr == NULL && size != 0)
 		bb_error_msg_and_die(bb_msg_memory_exhausted);
 	return ptr;
 }
 #endif /* DMALLOC */

 // Die if we can't allocate and zero size bytes of memory.
 void* FAST_FUNC xzalloc(size_t size)
 {
 	void *ptr = xmalloc(size);
 	memset(ptr, 0, size);
 	return ptr;
 }

 // Die if we can't copy a string to freshly allocated memory.
 char* FAST_FUNC xstrdup(const char *s)
 {
 	char *t;

 	if (s == NULL)
 		return NULL;

 	t = strdup(s);

 	if (t == NULL)
 		bb_error_msg_and_die(bb_msg_memory_exhausted);

 	return t;
 }

 // Die if we can't allocate n+1 bytes (space for the null terminator) and copy
 // the (possibly truncated to length n) string into it.
 char* FAST_FUNC xstrndup(const char *s, int n)
 {
 	int m;
 	char *t;

 	if (ENABLE_DEBUG && s == NULL)
 		bb_error_msg_and_die("xstrndup bug");

 	/* We can just xmalloc(n+1) and strncpy into it, */
 	/* but think about xstrndup("abc", 10000) wastage! */
 	m = n;
 	t = (char*) s;
 	while (m) {
 		if (!*t) break;
 		m--;
 		t++;
 	}
 	n -= m;
 	t = xmalloc(n + 1);
 	t[n] = '\0';

 	return memcpy(t, s, n);
 }

 // Die if we can't open a file and return a FILE* to it.
 // Notice we haven't got xfread(), This is for use with fscanf() and friends.
 FILE* FAST_FUNC xfopen(const char *path, const char *mode)
 {
 	FILE *fp = fopen(path, mode);
 	if (fp == NULL)
 		bb_perror_msg_and_die("can't open '%s'", path);
 	return fp;
 }

 // Die if we can't open a file and return a fd.
 int FAST_FUNC xopen3(const char *pathname, int flags, int mode)
 {
 	int ret;

 	ret = open(pathname, flags, mode);
 	if (ret < 0) {
 		bb_perror_msg_and_die("can't open '%s'", pathname);
 	}
 	return ret;
 }

 // Die if we can't open an existing file and return a fd.
 int FAST_FUNC xopen(const char *pathname, int flags)
 {
 	return xopen3(pathname, flags, 0666);
 }

 // Warn if we can't open a file and return a fd.
 int FAST_FUNC open3_or_warn(const char *pathname, int flags, int mode)
 {
 	int ret;

 	ret = open(pathname, flags, mode);
 	if (ret < 0) {
 		bb_perror_msg("can't open '%s'", pathname);
 	}
 	return ret;
 }

 // Warn if we can't open a file and return a fd.
 int FAST_FUNC open_or_warn(const char *pathname, int flags)
 {
 	return open3_or_warn(pathname, flags, 0666);
 }

 void FAST_FUNC xunlink(const char *pathname)
 {
 	if (unlink(pathname))
 		bb_perror_msg_and_die("can't remove file '%s'", pathname);
 }

 void FAST_FUNC xrename(const char *oldpath, const char *newpath)
 {
 	if (rename(oldpath, newpath))
 		bb_perror_msg_and_die("can't move '%s' to '%s'", oldpath, newpath);
 }

 int FAST_FUNC rename_or_warn(const char *oldpath, const char *newpath)
 {
 	int n = rename(oldpath, newpath);
 	if (n)
 		bb_perror_msg("can't move '%s' to '%s'", oldpath, newpath);
 	return n;
 }

 void FAST_FUNC xpipe(int filedes[2])
 {
 	if (pipe(filedes))
 		bb_perror_msg_and_die("can't create pipe");
 }

 void FAST_FUNC xdup2(int from, int to)
 {
 	if (dup2(from, to) != to)
 		bb_perror_msg_and_die("can't duplicate file descriptor");
 }

 // "Renumber" opened fd
 void FAST_FUNC xmove_fd(int from, int to)
 {
 	if (from == to)
 		return;
 	xdup2(from, to);
 	close(from);
 }

 // Die with an error message if we can't write the entire buffer.
 void FAST_FUNC xwrite(int fd, const void *buf, size_t count)
 {
 	if (count) {
 		ssize_t size = full_write(fd, buf, count);
 		if ((size_t)size != count)
 			bb_error_msg_and_die("short write");
 	}
 }
 void FAST_FUNC xwrite_str(int fd, const char *str)
 {
 	xwrite(fd, str, strlen(str));
 }

 // Die with an error message if we can't lseek to the right spot.
 off_t FAST_FUNC xlseek(int fd, off_t offset, int whence)
 {
 	off_t off = lseek(fd, offset, whence);
 	if (off == (off_t)-1) {
 		if (whence == SEEK_SET)
 			bb_perror_msg_and_die("lseek(%"OFF_FMT"u)", offset);
 		bb_perror_msg_and_die("lseek");
 	}
 	return off;
 }

 // Die with supplied filename if this FILE* has ferror set.
 void FAST_FUNC die_if_ferror(FILE *fp, const char *fn)
 {
 	if (ferror(fp)) {
 		/* ferror doesn't set useful errno */
 		bb_error_msg_and_die("%s: I/O error", fn);
 	}
 }

 // Die with an error message if stdout has ferror set.
 void FAST_FUNC die_if_ferror_stdout(void)
 {
 	die_if_ferror(stdout, bb_msg_standard_output);
 }

 // Die with an error message if we have trouble flushing stdout.
 void FAST_FUNC xfflush_stdout(void)
 {
 	if (fflush(stdout)) {
 		bb_perror_msg_and_die(bb_msg_standard_output);
 	}
 }


 int FAST_FUNC bb_putchar(int ch)
 {
 	/* time.c needs putc(ch, stdout), not putchar(ch).
 	 * it does "stdout = stderr;", but then glibc's putchar()
 	 * doesn't work as expected. bad glibc, bad */
 	return putc(ch, stdout);
 }

 /* Die with an error message if we can't copy an entire FILE* to stdout,
  * then close that file. */
 void FAST_FUNC xprint_and_close_file(FILE *file)
 {
 	fflush(stdout);
 	// copyfd outputs error messages for us.
 	if (bb_copyfd_eof(fileno(file), 1) == -1)
 		xfunc_die();

 	fclose(file);
 }

 // Die with an error message if we can't malloc() enough space and do an
 // sprintf() into that space.
 char* FAST_FUNC xasprintf(const char *format, ...)
 {
 	va_list p;
 	int r;
 	char *string_ptr;

 #if 1
 	// GNU extension
 	va_start(p, format);
 	r = vasprintf(&string_ptr, format, p);
 	va_end(p);
 #else
 	// Bloat for systems that haven't got the GNU extension.
 	va_start(p, format);
 	r = vsnprintf(NULL, 0, format, p);
 	va_end(p);
 	string_ptr = xmalloc(r+1);
 	va_start(p, format);
 	r = vsnprintf(string_ptr, r+1, format, p);
 	va_end(p);
 #endif

 	if (r < 0)
 		bb_error_msg_and_die(bb_msg_memory_exhausted);
 	return string_ptr;
 }

 #if 0 /* If we will ever meet a libc which hasn't [f]dprintf... */
 int FAST_FUNC fdprintf(int fd, const char *format, ...)
 {
 	va_list p;
 	int r;
 	char *string_ptr;

 #if 1
 	// GNU extension
 	va_start(p, format);
 	r = vasprintf(&string_ptr, format, p);
 	va_end(p);
 #else
 	// Bloat for systems that haven't got the GNU extension.
 	va_start(p, format);
 	r = vsnprintf(NULL, 0, format, p) + 1;
 	va_end(p);
 	string_ptr = malloc(r);
 	if (string_ptr) {
 		va_start(p, format);
 		r = vsnprintf(string_ptr, r, format, p);
 		va_end(p);
 	}
 #endif

 	if (r >= 0) {
 		full_write(fd, string_ptr, r);
 		free(string_ptr);
 	}
 	return r;
 }
 #endif

 void FAST_FUNC xsetenv(const char *key, const char *value)
 {
 	if (setenv(key, value, 1))
 		bb_error_msg_and_die(bb_msg_memory_exhausted);
 }

 /* Handles "VAR=VAL" strings, even those which are part of environ
  * _right now_
  */
 void FAST_FUNC bb_unsetenv(const char *var)
 {
 	char *tp = strchr(var, '=');

 	if (!tp) {
 		unsetenv(var);
 		return;
 	}

 	/* In case var was putenv'ed, we can't replace '='
 	 * with NUL and unsetenv(var) - it won't work,
 	 * env is modified by the replacement, unsetenv
 	 * sees "VAR" instead of "VAR=VAL" and does not remove it!
 	 * horror :( */
 	tp = xstrndup(var, tp - var);
 	unsetenv(tp);
 	free(tp);
 }


 // Die with an error message if we can't set gid.  (Because resource limits may
 // limit this user to a given number of processes, and if that fills up the
 // setgid() will fail and we'll _still_be_root_, which is bad.)
 void FAST_FUNC xsetgid(gid_t gid)
 {
 	if (setgid(gid)) bb_perror_msg_and_die("setgid");
 }

 // Die with an error message if we can't set uid.  (See xsetgid() for why.)
 void FAST_FUNC xsetuid(uid_t uid)
 {
 	if (setuid(uid)) bb_perror_msg_and_die("setuid");
 }

 // Die if we can't chdir to a new path.
 void FAST_FUNC xchdir(const char *path)
 {
 	if (chdir(path))
 		bb_perror_msg_and_die("chdir(%s)", path);
 }

 void FAST_FUNC xchroot(const char *path)
 {
 	if (chroot(path))
 		bb_perror_msg_and_die("can't change root directory to %s", path);
 }

 // Print a warning message if opendir() fails, but don't die.
 DIR* FAST_FUNC warn_opendir(const char *path)
 {
 	DIR *dp;

 	dp = opendir(path);
 	if (!dp)
 		bb_perror_msg("can't open '%s'", path);
 	return dp;
 }

 // Die with an error message if opendir() fails.
 DIR* FAST_FUNC xopendir(const char *path)
 {
 	DIR *dp;

 	dp = opendir(path);
 	if (!dp)
 		bb_perror_msg_and_die("can't open '%s'", path);
 	return dp;
 }

 // Die with an error message if we can't open a new socket.
 int FAST_FUNC xsocket(int domain, int type, int protocol)
 {
 	int r = socket(domain, type, protocol);

 	if (r < 0) {
 		/* Hijack vaguely related config option */
 #if ENABLE_VERBOSE_RESOLUTION_ERRORS
 		const char *s = "INET";
 		if (domain == AF_PACKET) s = "PACKET";
 		if (domain == AF_NETLINK) s = "NETLINK";
 IF_FEATURE_IPV6(if (domain == AF_INET6) s = "INET6";)
 		bb_perror_msg_and_die("socket(AF_%s)", s);
 #else
 		bb_perror_msg_and_die("socket");
 #endif
 	}

 	return r;
 }

 // Die with an error message if we can't bind a socket to an address.
 void FAST_FUNC xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen)
 {
 	if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind");
 }

 // Die with an error message if we can't listen for connections on a socket.
 void FAST_FUNC xlisten(int s, int backlog)
 {
 	if (listen(s, backlog)) bb_perror_msg_and_die("listen");
 }

 /* Die with an error message if sendto failed.
  * Return bytes sent otherwise  */
 ssize_t FAST_FUNC xsendto(int s, const void *buf, size_t len, const struct sockaddr *to,
 				socklen_t tolen)
 {
 	ssize_t ret = sendto(s, buf, len, 0, to, tolen);
 	if (ret < 0) {
 		if (ENABLE_FEATURE_CLEAN_UP)
 			close(s);
 		bb_perror_msg_and_die("sendto");
 	}
 	return ret;
 }

 // xstat() - a stat() which dies on failure with meaningful error message
 void FAST_FUNC xstat(const char *name, struct stat *stat_buf)
 {
 	if (stat(name, stat_buf))
 		bb_perror_msg_and_die("can't stat '%s'", name);
 }

 // selinux_or_die() - die if SELinux is disabled.
 void FAST_FUNC selinux_or_die(void)
 {
 #if ENABLE_SELINUX
 	int rc = is_selinux_enabled();
 	if (rc == 0) {
 		bb_error_msg_and_die("SELinux is disabled");
 	} else if (rc < 0) {
 		bb_error_msg_and_die("is_selinux_enabled() failed");
 	}
 #else
 	bb_error_msg_and_die("SELinux support is disabled");
 #endif
 }

 int FAST_FUNC ioctl_or_perror_and_die(int fd, unsigned request, void *argp, const char *fmt,...)
 {
 	int ret;
 	va_list p;

 	ret = ioctl(fd, request, argp);
 	if (ret < 0) {
 		va_start(p, fmt);
 		bb_verror_msg(fmt, p, strerror(errno));
 		/* xfunc_die can actually longjmp, so be nice */
 		va_end(p);
 		xfunc_die();
 	}
 	return ret;
 }

 int FAST_FUNC ioctl_or_perror(int fd, unsigned request, void *argp, const char *fmt,...)
 {
 	va_list p;
 	int ret = ioctl(fd, request, argp);

 	if (ret < 0) {
 		va_start(p, fmt);
 		bb_verror_msg(fmt, p, strerror(errno));
 		va_end(p);
 	}
 	return ret;
 }

 #if ENABLE_IOCTL_HEX2STR_ERROR
 int FAST_FUNC bb_ioctl_or_warn(int fd, unsigned request, void *argp, const char *ioctl_name)
 {
 	int ret;

 	ret = ioctl(fd, request, argp);
 	if (ret < 0)
 		bb_simple_perror_msg(ioctl_name);
 	return ret;
 }
 int FAST_FUNC bb_xioctl(int fd, unsigned request, void *argp, const char *ioctl_name)
 {
 	int ret;

 	ret = ioctl(fd, request, argp);
 	if (ret < 0)
 		bb_simple_perror_msg_and_die(ioctl_name);
 	return ret;
 }
 #else
 int FAST_FUNC bb_ioctl_or_warn(int fd, unsigned request, void *argp)
 {
 	int ret;

 	ret = ioctl(fd, request, argp);
 	if (ret < 0)
 		bb_perror_msg("ioctl %#x failed", request);
 	return ret;
 }
 int FAST_FUNC bb_xioctl(int fd, unsigned request, void *argp)
 {
 	int ret;

 	ret = ioctl(fd, request, argp);
 	if (ret < 0)
 		bb_perror_msg_and_die("ioctl %#x failed", request);
 	return ret;
 }
 #endif
	/* vi: set sw=4 ts=4: */
	/*
	* Utility routines.
	*
	* Copyright (C) 1999-2004 by Erik Andersen <andersen@codepoet.org>
	* Copyright (C) 2006 Rob Landley
	* Copyright (C) 2006 Denys Vlasenko
	*
	* Licensed under GPL version 2, see file LICENSE in this tarball for details.
	*/

	/* We need to have separate xfuncs.c and xfuncs_printf.c because
	* with current linkers, even with section garbage collection,
	* if *.o module references any of XXXprintf functions, you pull in
	* entire printf machinery. Even if you do not use the function
	* which uses XXXprintf.
	*
	* xfuncs.c contains functions (not necessarily xfuncs)
	* which do not pull in printf, directly or indirectly.
	* xfunc_printf.c contains those which do.
	*/

	#include "libbb.h"


	/* All the functions starting with "x" call bb_error_msg_and_die() if they
	* fail, so callers never need to check for errors. If it returned, it
	* succeeded. */

	#ifndef DMALLOC
	/* dmalloc provides variants of these that do abort() on failure.
	* Since dmalloc's prototypes overwrite the impls here as they are
	* included after these prototypes in libbb.h, all is well.
	*/
	// Warn if we can't allocate size bytes of memory.
	void* FAST_FUNC malloc_or_warn(size_t size)
	{
	void *ptr = malloc(size);
	if (ptr == NULL && size != 0)
	bb_error_msg(bb_msg_memory_exhausted);
	return ptr;
	}

	// Die if we can't allocate size bytes of memory.
	void* FAST_FUNC xmalloc(size_t size)
	{
	void *ptr = malloc(size);
	if (ptr == NULL && size != 0)
	bb_error_msg_and_die(bb_msg_memory_exhausted);
	return ptr;
	}

	// Die if we can't resize previously allocated memory. (This returns a pointer
	// to the new memory, which may or may not be the same as the old memory.
	// It'll copy the contents to a new chunk and free the old one if necessary.)
	void* FAST_FUNC xrealloc(void *ptr, size_t size)
	{
	ptr = realloc(ptr, size);
	if (ptr == NULL && size != 0)
	bb_error_msg_and_die(bb_msg_memory_exhausted);
	return ptr;
	}
	#endif /* DMALLOC */

	// Die if we can't allocate and zero size bytes of memory.
	void* FAST_FUNC xzalloc(size_t size)
	{
	void *ptr = xmalloc(size);
	memset(ptr, 0, size);
	return ptr;
	}

	// Die if we can't copy a string to freshly allocated memory.
	char* FAST_FUNC xstrdup(const char *s)
	{
	char *t;

	if (s == NULL)
	return NULL;

	t = strdup(s);

	if (t == NULL)
	bb_error_msg_and_die(bb_msg_memory_exhausted);

	return t;
	}

	// Die if we can't allocate n+1 bytes (space for the null terminator) and copy
	// the (possibly truncated to length n) string into it.
	char* FAST_FUNC xstrndup(const char *s, int n)
	{
	int m;
	char *t;

	if (ENABLE_DEBUG && s == NULL)
	bb_error_msg_and_die("xstrndup bug");

	/* We can just xmalloc(n+1) and strncpy into it, */
	/* but think about xstrndup("abc", 10000) wastage! */
	m = n;
	t = (char*) s;
	while (m) {
	if (!*t) break;
	m--;
	t++;
	}
	n -= m;
	t = xmalloc(n + 1);
	t[n] = '\0';

	return memcpy(t, s, n);
	}

	// Die if we can't open a file and return a FILE* to it.
	// Notice we haven't got xfread(), This is for use with fscanf() and friends.
	FILE* FAST_FUNC xfopen(const char path, const char mode)
	{
	FILE *fp = fopen(path, mode);
	if (fp == NULL)
	bb_perror_msg_and_die("can't open '%s'", path);
	return fp;
	}

	// Die if we can't open a file and return a fd.
	int FAST_FUNC xopen3(const char *pathname, int flags, int mode)
	{
	int ret;

	ret = open(pathname, flags, mode);
	if (ret < 0) {
	bb_perror_msg_and_die("can't open '%s'", pathname);
	}
	return ret;
	}

	// Die if we can't open an existing file and return a fd.
	int FAST_FUNC xopen(const char *pathname, int flags)
	{
	return xopen3(pathname, flags, 0666);
	}

	// Warn if we can't open a file and return a fd.
	int FAST_FUNC open3_or_warn(const char *pathname, int flags, int mode)
	{
	int ret;

	ret = open(pathname, flags, mode);
	if (ret < 0) {
	bb_perror_msg("can't open '%s'", pathname);
	}
	return ret;
	}

	// Warn if we can't open a file and return a fd.
	int FAST_FUNC open_or_warn(const char *pathname, int flags)
	{
	return open3_or_warn(pathname, flags, 0666);
	}

	void FAST_FUNC xunlink(const char *pathname)
	{
	if (unlink(pathname))
	bb_perror_msg_and_die("can't remove file '%s'", pathname);
	}

	void FAST_FUNC xrename(const char oldpath, const char newpath)
	{
	if (rename(oldpath, newpath))
	bb_perror_msg_and_die("can't move '%s' to '%s'", oldpath, newpath);
	}

	int FAST_FUNC rename_or_warn(const char oldpath, const char newpath)
	{
	int n = rename(oldpath, newpath);
	if (n)
	bb_perror_msg("can't move '%s' to '%s'", oldpath, newpath);
	return n;
	}

	void FAST_FUNC xpipe(int filedes[2])
	{
	if (pipe(filedes))
	bb_perror_msg_and_die("can't create pipe");
	}

	void FAST_FUNC xdup2(int from, int to)
	{
	if (dup2(from, to) != to)
	bb_perror_msg_and_die("can't duplicate file descriptor");
	}

	// "Renumber" opened fd
	void FAST_FUNC xmove_fd(int from, int to)
	{
	if (from == to)
	return;
	xdup2(from, to);
	close(from);
	}

	// Die with an error message if we can't write the entire buffer.
	void FAST_FUNC xwrite(int fd, const void *buf, size_t count)
	{
	if (count) {
	ssize_t size = full_write(fd, buf, count);
	if ((size_t)size != count)
	bb_error_msg_and_die("short write");
	}
	}
	void FAST_FUNC xwrite_str(int fd, const char *str)
	{
	xwrite(fd, str, strlen(str));
	}

	// Die with an error message if we can't lseek to the right spot.
	off_t FAST_FUNC xlseek(int fd, off_t offset, int whence)
	{
	off_t off = lseek(fd, offset, whence);
	if (off == (off_t)-1) {
	if (whence == SEEK_SET)
	bb_perror_msg_and_die("lseek(%"OFF_FMT"u)", offset);
	bb_perror_msg_and_die("lseek");
	}
	return off;
	}

	// Die with supplied filename if this FILE* has ferror set.
	void FAST_FUNC die_if_ferror(FILE fp, const char fn)
	{
	if (ferror(fp)) {
	/* ferror doesn't set useful errno */
	bb_error_msg_and_die("%s: I/O error", fn);
	}
	}

	// Die with an error message if stdout has ferror set.
	void FAST_FUNC die_if_ferror_stdout(void)
	{
	die_if_ferror(stdout, bb_msg_standard_output);
	}

	// Die with an error message if we have trouble flushing stdout.
	void FAST_FUNC xfflush_stdout(void)
	{
	if (fflush(stdout)) {
	bb_perror_msg_and_die(bb_msg_standard_output);
	}
	}


	int FAST_FUNC bb_putchar(int ch)
	{
	/* time.c needs putc(ch, stdout), not putchar(ch).
	* it does "stdout = stderr;", but then glibc's putchar()
	* doesn't work as expected. bad glibc, bad */
	return putc(ch, stdout);
	}

	/* Die with an error message if we can't copy an entire FILE* to stdout,
	* then close that file. */
	void FAST_FUNC xprint_and_close_file(FILE *file)
	{
	fflush(stdout);
	// copyfd outputs error messages for us.
	if (bb_copyfd_eof(fileno(file), 1) == -1)
	xfunc_die();

	fclose(file);
	}

	// Die with an error message if we can't malloc() enough space and do an
	// sprintf() into that space.
	char* FAST_FUNC xasprintf(const char *format, ...)
	{
	va_list p;
	int r;
	char *string_ptr;

	#if 1
	// GNU extension
	va_start(p, format);
	r = vasprintf(&string_ptr, format, p);
	va_end(p);
	#else
	// Bloat for systems that haven't got the GNU extension.
	va_start(p, format);
	r = vsnprintf(NULL, 0, format, p);
	va_end(p);
	string_ptr = xmalloc(r+1);
	va_start(p, format);
	r = vsnprintf(string_ptr, r+1, format, p);
	va_end(p);
	#endif

	if (r < 0)
	bb_error_msg_and_die(bb_msg_memory_exhausted);
	return string_ptr;
	}

	#if 0 /* If we will ever meet a libc which hasn't [f]dprintf... */
	int FAST_FUNC fdprintf(int fd, const char *format, ...)
	{
	va_list p;
	int r;
	char *string_ptr;

	#if 1
	// GNU extension
	va_start(p, format);
	r = vasprintf(&string_ptr, format, p);
	va_end(p);
	#else
	// Bloat for systems that haven't got the GNU extension.
	va_start(p, format);
	r = vsnprintf(NULL, 0, format, p) + 1;
	va_end(p);
	string_ptr = malloc(r);
	if (string_ptr) {
	va_start(p, format);
	r = vsnprintf(string_ptr, r, format, p);
	va_end(p);
	}
	#endif

	if (r >= 0) {
	full_write(fd, string_ptr, r);
	free(string_ptr);
	}
	return r;
	}
	#endif

	void FAST_FUNC xsetenv(const char key, const char value)
	{
	if (setenv(key, value, 1))
	bb_error_msg_and_die(bb_msg_memory_exhausted);
	}

	/* Handles "VAR=VAL" strings, even those which are part of environ
	* _right now_
	*/
	void FAST_FUNC bb_unsetenv(const char *var)
	{
	char *tp = strchr(var, '=');

	if (!tp) {
	unsetenv(var);
	return;
	}

	/* In case var was putenv'ed, we can't replace '='
	* with NUL and unsetenv(var) - it won't work,
	* env is modified by the replacement, unsetenv
	* sees "VAR" instead of "VAR=VAL" and does not remove it!
	* horror :( */
	tp = xstrndup(var, tp - var);
	unsetenv(tp);
	free(tp);
	}


	// Die with an error message if we can't set gid. (Because resource limits may
	// limit this user to a given number of processes, and if that fills up the
	// setgid() will fail and we'll _still_be_root_, which is bad.)
	void FAST_FUNC xsetgid(gid_t gid)
	{
	if (setgid(gid)) bb_perror_msg_and_die("setgid");
	}

	// Die with an error message if we can't set uid. (See xsetgid() for why.)
	void FAST_FUNC xsetuid(uid_t uid)
	{
	if (setuid(uid)) bb_perror_msg_and_die("setuid");
	}

	// Die if we can't chdir to a new path.
	void FAST_FUNC xchdir(const char *path)
	{
	if (chdir(path))
	bb_perror_msg_and_die("chdir(%s)", path);
	}

	void FAST_FUNC xchroot(const char *path)
	{
	if (chroot(path))
	bb_perror_msg_and_die("can't change root directory to %s", path);
	}

	// Print a warning message if opendir() fails, but don't die.
	DIR* FAST_FUNC warn_opendir(const char *path)
	{
	DIR *dp;

	dp = opendir(path);
	if (!dp)
	bb_perror_msg("can't open '%s'", path);
	return dp;
	}

	// Die with an error message if opendir() fails.
	DIR* FAST_FUNC xopendir(const char *path)
	{
	DIR *dp;

	dp = opendir(path);
	if (!dp)
	bb_perror_msg_and_die("can't open '%s'", path);
	return dp;
	}

	// Die with an error message if we can't open a new socket.
	int FAST_FUNC xsocket(int domain, int type, int protocol)
	{
	int r = socket(domain, type, protocol);

	if (r < 0) {
	/* Hijack vaguely related config option */
	#if ENABLE_VERBOSE_RESOLUTION_ERRORS
	const char *s = "INET";
	if (domain == AF_PACKET) s = "PACKET";
	if (domain == AF_NETLINK) s = "NETLINK";
	IF_FEATURE_IPV6(if (domain == AF_INET6) s = "INET6";)
	bb_perror_msg_and_die("socket(AF_%s)", s);
	#else
	bb_perror_msg_and_die("socket");
	#endif
	}

	return r;
	}

	// Die with an error message if we can't bind a socket to an address.
	void FAST_FUNC xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen)
	{
	if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind");
	}

	// Die with an error message if we can't listen for connections on a socket.
	void FAST_FUNC xlisten(int s, int backlog)
	{
	if (listen(s, backlog)) bb_perror_msg_and_die("listen");
	}

	/* Die with an error message if sendto failed.
	* Return bytes sent otherwise */
	ssize_t FAST_FUNC xsendto(int s, const void buf, size_t len, const struct sockaddr to,
	socklen_t tolen)
	{
	ssize_t ret = sendto(s, buf, len, 0, to, tolen);
	if (ret < 0) {
	if (ENABLE_FEATURE_CLEAN_UP)
	close(s);
	bb_perror_msg_and_die("sendto");
	}
	return ret;
	}

	// xstat() - a stat() which dies on failure with meaningful error message
	void FAST_FUNC xstat(const char name, struct stat stat_buf)
	{
	if (stat(name, stat_buf))
	bb_perror_msg_and_die("can't stat '%s'", name);
	}

	// selinux_or_die() - die if SELinux is disabled.
	void FAST_FUNC selinux_or_die(void)
	{
	#if ENABLE_SELINUX
	int rc = is_selinux_enabled();
	if (rc == 0) {
	bb_error_msg_and_die("SELinux is disabled");
	} else if (rc < 0) {
	bb_error_msg_and_die("is_selinux_enabled() failed");
	}
	#else
	bb_error_msg_and_die("SELinux support is disabled");
	#endif
	}

	int FAST_FUNC ioctl_or_perror_and_die(int fd, unsigned request, void argp, const char fmt,...)
	{
	int ret;
	va_list p;

	ret = ioctl(fd, request, argp);
	if (ret < 0) {
	va_start(p, fmt);
	bb_verror_msg(fmt, p, strerror(errno));
	/* xfunc_die can actually longjmp, so be nice */
	va_end(p);
	xfunc_die();
	}
	return ret;
	}

	int FAST_FUNC ioctl_or_perror(int fd, unsigned request, void argp, const char fmt,...)
	{
	va_list p;
	int ret = ioctl(fd, request, argp);

	if (ret < 0) {
	va_start(p, fmt);
	bb_verror_msg(fmt, p, strerror(errno));
	va_end(p);
	}
	return ret;
	}

	#if ENABLE_IOCTL_HEX2STR_ERROR
	int FAST_FUNC bb_ioctl_or_warn(int fd, unsigned request, void argp, const char ioctl_name)
	{
	int ret;

	ret = ioctl(fd, request, argp);
	if (ret < 0)
	bb_simple_perror_msg(ioctl_name);
	return ret;
	}
	int FAST_FUNC bb_xioctl(int fd, unsigned request, void argp, const char ioctl_name)
	{
	int ret;

	ret = ioctl(fd, request, argp);
	if (ret < 0)
	bb_simple_perror_msg_and_die(ioctl_name);
	return ret;
	}
	#else
	int FAST_FUNC bb_ioctl_or_warn(int fd, unsigned request, void *argp)
	{
	int ret;

	ret = ioctl(fd, request, argp);
	if (ret < 0)
	bb_perror_msg("ioctl %#x failed", request);
	return ret;
	}
	int FAST_FUNC bb_xioctl(int fd, unsigned request, void *argp)
	{
	int ret;

	ret = ioctl(fd, request, argp);
	if (ret < 0)
	bb_perror_msg_and_die("ioctl %#x failed", request);
	return ret;
	}
	#endif