[oweals/busybox.git] / libbb / xfuncs.c

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

#ifdef L_xrealloc
// 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)
                bb_error_msg_and_die(bb_msg_memory_exhausted);
        return ptr;
}
#endif
#endif /* DMALLOC */


#ifdef L_xzalloc
// 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;
}
#endif

#ifdef L_xstrdup
// 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)
                bb_error_msg_and_die(bb_msg_memory_exhausted);

        return t;
}
#endif

#ifdef L_xstrndup
// 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);
}
#endif

#ifdef L_xfopen
// 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)
                bb_perror_msg_and_die("%s", path);
        return fp;
}
#endif

#ifdef L_xopen
// 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, 0777);
}
#endif

#ifdef L_xopen3
// Die if we can't open a new file and return an fd.
int xopen3(const char *pathname, int flags, int mode)
{
        int ret;

        ret = open(pathname, flags, mode);
        if (ret < 0) {
                bb_perror_msg_and_die("%s", pathname);
        }
        return ret;
}
#endif

#ifdef L_xread
// Die with an error message if we can't read the entire buffer.
void xread(int fd, void *buf, size_t count)
{
        while (count) {
                ssize_t size;

                if ((size = safe_read(fd, buf, count)) < 1)
                        bb_error_msg_and_die("Short read");
                count -= size;
                buf = ((char *) buf) + size;
        }
}
#endif

#ifdef L_xwrite
// Die with an error message if we can't write the entire buffer.
void xwrite(int fd, void *buf, size_t count)
{
        while (count) {
                ssize_t size;

                if ((size = safe_write(fd, buf, count)) < 1)
                        bb_error_msg_and_die("Short write");
                count -= size;
                buf = ((char *) buf) + size;
        }
}
#endif

#ifdef L_xlseek
// Die with an error message if we can't lseek to the right spot.
void xlseek(int fd, off_t offset, int whence)
{
        if (offset != lseek(fd, offset, whence)) bb_error_msg_and_die("lseek");
}
#endif

#ifdef L_xread_char
// Die with an error message if we can't read one character.
unsigned char xread_char(int fd)
{
        char tmp;

        xread(fd, &tmp, 1);

        return(tmp);
}
#endif

#ifdef L_xferror
// Die with supplied error message if this FILE * has ferror set.
void xferror(FILE *fp, const char *fn)
{
        if (ferror(fp)) {
                bb_error_msg_and_die("%s", fn);
        }
}
#endif

#ifdef L_xferror_stdout
// Die with an error message if stdout has ferror set.
void xferror_stdout(void)
{
        xferror(stdout, bb_msg_standard_output);
}
#endif

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

#ifdef L_spawn
// 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;
}
#endif

#ifdef L_xspawn
// 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;
}
#endif

#ifdef L_wait4
// 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;
}
#endif

#ifdef L_xsetenv
void xsetenv(const char *key, const char *value)
{
        if(setenv(key, value, 1))
                bb_error_msg_and_die(bb_msg_memory_exhausted);
}
#endif

#ifdef L_itoa
// 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;
}
#endif

#ifdef L_setuid
// 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 cant' set uid.  (See xsetgid() for why.)
void xsetuid(uid_t uid)
{
        if (setuid(uid)) bb_error_msg_and_die("setuid");
}
#endif

#ifdef L_fdlength
// 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;

        // 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, 0)>=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;
}
#endif

#ifdef L_xasprintf
// 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;
}
#endif

#ifdef L_xprint_and_close_file
// 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)
{
        // copyfd outputs error messages for us.
        if (bb_copyfd_eof(fileno(file), 1) == -1)
                exit(bb_default_error_retval);

        fclose(file);
}
#endif

#ifdef L_xchdir
// 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);
}
#endif

#ifdef L_warn_opendir
// 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;
}
#endif

#ifdef L_xopendir
// 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;
}
#endif

#ifdef L_xdaemon
#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
#endif

#ifdef L_xsocket
// 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;
}
#endif

#ifdef L_xbind
// 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");
}
#endif

#ifdef L_xlisten
// 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");
}
#endif

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

#ifdef L_get_terminal_width_height
/* 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 (!win.ws_row) {
                char *s = getenv("LINES");
                if (s) win.ws_row = atoi(s);
        }
        if (win.ws_row <= 1) win.ws_row = 24;
        if (!win.ws_col) {
                char *s = getenv("COLUMNS");
                if (s) win.ws_col = atoi(s);
        }
        if (win.ws_col <= 1) win.ws_col = 80;
        if (height) *height = (int) win.ws_row;
        if (width) *width = (int) win.ws_col;

        return ret;
}
#endif