busybox/libbb/xfuncs.c

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/* 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 Denis Vlasenko
*
* Licensed under GPL version 2, see file LICENSE in this tarball for details.
*/
#include "busybox.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.
*/
// Die if we can't allocate size bytes of memory.
void *xmalloc(size_t size)
{
void *ptr = malloc(size);
if (ptr == NULL && size != 0)
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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 *xrealloc(void *ptr, size_t size)
{
ptr = realloc(ptr, size);
if (ptr == NULL && size != 0)
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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 *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 * xstrdup(const char *s)
{
char *t;
if (s == NULL)
return NULL;
t = strdup (s);
if (t == NULL)
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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 * xstrndup(const char *s, int n)
{
char *t;
if (ENABLE_DEBUG && s == NULL)
bb_error_msg_and_die("xstrndup bug");
t = xmalloc(++n);
return safe_strncpy(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 *xfopen(const char *path, const char *mode)
{
FILE *fp;
if ((fp = fopen(path, mode)) == NULL)
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bb_perror_msg_and_die("%s", path);
return fp;
}
// Die if we can't open an existing file and return an fd.
int xopen(const char *pathname, int flags)
{
if (ENABLE_DEBUG && (flags & O_CREAT))
bb_error_msg_and_die("xopen() with O_CREAT");
return xopen3(pathname, flags, 0666);
}
// Die if we can't open a new file and return an fd.
int xopen3(const char *pathname, int flags, int mode)
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{
int ret;
ret = open(pathname, flags, mode);
if (ret < 0) {
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bb_perror_msg_and_die("%s", pathname);
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}
return ret;
}
// Die with an error message if we can't write the entire buffer.
void xwrite(int fd, void *buf, size_t count)
{
if (count) {
ssize_t size = full_write(fd, buf, count);
if (size != count)
bb_error_msg_and_die("short write");
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}
}
// Die with an error message if we can't lseek to the right spot.
off_t xlseek(int fd, off_t offset, int whence)
{
off_t off = lseek(fd, offset, whence);
if (off == (off_t)-1)
bb_perror_msg_and_die("lseek");
return off;
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}
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// Die with supplied error message if this FILE * has ferror set.
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void die_if_ferror(FILE *fp, const char *fn)
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{
if (ferror(fp)) {
bb_error_msg_and_die("%s", fn);
}
}
// Die with an error message if stdout has ferror set.
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void die_if_ferror_stdout(void)
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{
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die_if_ferror(stdout, bb_msg_standard_output);
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}
// Die with an error message if we have trouble flushing stdout.
void xfflush_stdout(void)
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{
if (fflush(stdout)) {
bb_perror_msg_and_die(bb_msg_standard_output);
}
}
// This does a fork/exec in one call, using vfork(). Return PID of new child,
// -1 for failure. Runs argv[0], searching path if that has no / in it.
pid_t spawn(char **argv)
{
static int failed;
pid_t pid;
void *app = ENABLE_FEATURE_SH_STANDALONE_SHELL ? find_applet_by_name(argv[0]) : 0;
// Be nice to nommu machines.
failed = 0;
pid = vfork();
if (pid < 0) return pid;
if (!pid) {
execvp(app ? CONFIG_BUSYBOX_EXEC_PATH : *argv, argv);
// We're sharing a stack with blocked parent, let parent know we failed
// and then exit to unblock parent (but don't run atexit() stuff, which
// would screw up parent.)
failed = -1;
_exit(0);
}
return failed ? failed : pid;
}
// Die with an error message if we can't spawn a child process.
pid_t xspawn(char **argv)
{
pid_t pid = spawn(argv);
if (pid < 0) bb_perror_msg_and_die("%s", *argv);
return pid;
}
// Wait for the specified child PID to exit, returning child's error return.
int wait4pid(int pid)
{
int status;
if (pid == -1 || waitpid(pid, &status, 0) == -1) return -1;
if (WIFEXITED(status)) return WEXITSTATUS(status);
if (WIFSIGNALED(status)) return WTERMSIG(status);
return 0;
}
void xsetenv(const char *key, const char *value)
{
if (setenv(key, value, 1))
bb_error_msg_and_die(bb_msg_memory_exhausted);
}
// Convert unsigned integer to ascii, writing into supplied buffer. A
// truncated result is always null terminated (unless buflen is 0), and
// contains the first few digits of the result ala strncpy.
void utoa_to_buf(unsigned n, char *buf, unsigned buflen)
{
int i, out = 0;
if (buflen) {
for (i=1000000000; i; i/=10) {
int res = n/i;
if ((res || out || i == 1) && --buflen>0) {
out++;
n -= res*i;
*buf++ = '0' + res;
}
}
*buf = 0;
}
}
// Convert signed integer to ascii, like utoa_to_buf()
void itoa_to_buf(int n, char *buf, unsigned buflen)
{
if (buflen && n<0) {
n = -n;
*buf++ = '-';
buflen--;
}
utoa_to_buf((unsigned)n, buf, buflen);
}
// The following two functions use a static buffer, so calling either one a
// second time will overwrite previous results.
//
// The largest 32 bit integer is -2 billion plus null terminator, or 12 bytes.
// Int should always be 32 bits on any remotely Unix-like system, see
// http://www.unix.org/whitepapers/64bit.html for the reasons why.
static char local_buf[12];
// Convert unsigned integer to ascii using a static buffer (returned).
char *utoa(unsigned n)
{
utoa_to_buf(n, local_buf, sizeof(local_buf));
return local_buf;
}
// Convert signed integer to ascii using a static buffer (returned).
char *itoa(int n)
{
itoa_to_buf(n, local_buf, sizeof(local_buf));
return local_buf;
}
// 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 xsetgid(gid_t gid)
{
if (setgid(gid)) bb_error_msg_and_die("setgid");
}
// Die with an error message if we can't set uid. (See xsetgid() for why.)
void xsetuid(uid_t uid)
{
if (setuid(uid)) bb_error_msg_and_die("setuid");
}
// Return how long the file at fd is, if there's any way to determine it.
off_t fdlength(int fd)
{
off_t bottom = 0, top = 0, pos;
long size;
// If the ioctl works for this, return it.
if (ioctl(fd, BLKGETSIZE, &size) >= 0) return size*512;
// FIXME: explain why lseek(SEEK_END) is not used here!
// If not, do a binary search for the last location we can read. (Some
// block devices don't do BLKGETSIZE right.)
do {
char temp;
pos = bottom + (top - bottom) / 2;
// If we can read from the current location, it's bigger.
if (lseek(fd, pos, SEEK_SET)>=0 && safe_read(fd, &temp, 1)==1) {
if (bottom == top) bottom = top = (top+1) * 2;
else bottom = pos;
// If we can't, it's smaller.
} else {
if (bottom == top) {
if (!top) return 0;
bottom = top/2;
}
else top = pos;
}
} while (bottom + 1 != top);
return pos + 1;
}
// Die with an error message if we can't malloc() enough space and do an
// sprintf() into that space.
char *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;
}
// Die with an error message if we can't copy an entire FILE * to stdout, then
// close that file.
void xprint_and_close_file(FILE *file)
{
fflush(stdout);
// copyfd outputs error messages for us.
if (bb_copyfd_eof(fileno(file), 1) == -1)
exit(xfunc_error_retval);
fclose(file);
}
// Die if we can't chdir to a new path.
void xchdir(const char *path)
{
if (chdir(path))
bb_perror_msg_and_die("chdir(%s)", path);
}
// Print a warning message if opendir() fails, but don't die.
DIR *warn_opendir(const char *path)
{
DIR *dp;
if ((dp = opendir(path)) == NULL) {
bb_perror_msg("unable to open `%s'", path);
return NULL;
}
return dp;
}
// Die with an error message if opendir() fails.
DIR *xopendir(const char *path)
{
DIR *dp;
if ((dp = opendir(path)) == NULL)
bb_perror_msg_and_die("unable to open `%s'", path);
return dp;
}
#ifndef BB_NOMMU
// Die with an error message if we can't daemonize.
void xdaemon(int nochdir, int noclose)
{
if (daemon(nochdir, noclose))
bb_perror_msg_and_die("daemon");
}
#endif
// Die with an error message if we can't open a new socket.
int xsocket(int domain, int type, int protocol)
{
int r = socket(domain, type, protocol);
if (r < 0) bb_perror_msg_and_die("socket");
return r;
}
// Die with an error message if we can't bind a socket to an address.
void 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 xlisten(int s, int backlog)
{
if (listen(s, backlog)) bb_perror_msg_and_die("listen");
}
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// xstat() - a stat() which dies on failure with meaningful error message
void xstat(char *name, struct stat *stat_buf)
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{
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if (stat(name, stat_buf))
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bb_perror_msg_and_die("can't stat '%s'", name);
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}
/* It is perfectly ok to pass in a NULL for either width or for
* height, in which case that value will not be set. */
int get_terminal_width_height(int fd, int *width, int *height)
{
struct winsize win = { 0, 0, 0, 0 };
int ret = ioctl(fd, TIOCGWINSZ, &win);
if (height) {
if (!win.ws_row) {
char *s = getenv("LINES");
if (s) win.ws_row = atoi(s);
}
if (win.ws_row <= 1 || win.ws_row >= 30000)
win.ws_row = 24;
*height = (int) win.ws_row;
}
if (width) {
if (!win.ws_col) {
char *s = getenv("COLUMNS");
if (s) win.ws_col = atoi(s);
}
if (win.ws_col <= 1 || win.ws_col >= 30000)
win.ws_col = 80;
*width = (int) win.ws_col;
}
return ret;
}