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common.c

/* common.c - common useful functions

   Copyright (C) 2000  Russell Kroll <rkroll@exploits.org>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/

#include "common.h"

#include <ctype.h>
#include <syslog.h>
#include <pwd.h>
#include <grp.h>

/* the reason we define UPS_VERSION as a static string, rather than a
      macro, is to make dependency tracking easier (only common.o depends
      on nut_version_macro.h), and also to prevent all sources from
      having to be recompiled each time the version changes (they only
      need to be re-linked). */
#include "nut_version.h"
const char *UPS_VERSION = NUT_VERSION_MACRO;

      int   nut_debug_level = 0;
      static      int   upslog_flags = UPSLOG_STDERR;

static void xbit_set(int *val, int flag)
{
      *val = (*val |= flag);
}

static void xbit_clear(int *val, int flag)
{
      *val = (*val ^= (*val & flag));
}

static int xbit_test(int val, int flag)
{
      return ((val & flag) == flag);
}

/* enable writing upslog_with_errno() and upslogx() type messages to 
   the syslog */
void syslogbit_set(void)
{
      xbit_set(&upslog_flags, UPSLOG_SYSLOG);
}

/* get the syslog ready for us */
void open_syslog(const char *progname)
{
      int   opt;

      opt = LOG_PID;

      /* we need this to grab /dev/log before chroot */
#ifdef LOG_NDELAY
      opt |= LOG_NDELAY;
#endif

      openlog(progname, opt, LOG_FACILITY);
}

/* close ttys and become a daemon */
void background(void)
{
      int   pid;

      if ((pid = fork()) < 0)
            fatal_with_errno(EXIT_FAILURE, "Unable to enter background");

      xbit_set(&upslog_flags, UPSLOG_SYSLOG);
      xbit_clear(&upslog_flags, UPSLOG_STDERR);

      close(0);
      close(1);
      close(2);

      if (pid != 0) 
            _exit(EXIT_SUCCESS);          /* parent */

      /* child */

      /* make fds 0-2 point somewhere defined */
      if (open("/dev/null", O_RDWR) != 0)
            fatal_with_errno(EXIT_FAILURE, "open /dev/null");

      if (dup(0) == -1)
            fatal_with_errno(EXIT_FAILURE, "dup");

      if (dup(0) == -1)
            fatal_with_errno(EXIT_FAILURE, "dup");

#ifdef HAVE_SETSID
      setsid();         /* make a new session to dodge signals */
#endif

      upslogx(LOG_INFO, "Startup successful");
}

/* do this here to keep pwd/grp stuff out of the main files */
struct passwd *get_user_pwent(const char *name)
{
      struct passwd *r;
      errno = 0;
      if ((r = getpwnam(name)))
            return r;

      /* POSIX does not specify that "user not found" is an error, so
         some implementations of getpwnam() do not set errno when this
         happens. */
      if (errno == 0)
            fatalx(EXIT_FAILURE, "user %s not found", name);
      else
            fatal_with_errno(EXIT_FAILURE, "getpwnam(%s)", name);
            
      return NULL;  /* to make the compiler happy */
}

/* change to the user defined in the struct */
void become_user(struct passwd *pw)
{
      /* if we can't switch users, then don't even try */
      if ((geteuid() != 0) && (getuid() != 0))
            return;

      if (getuid() == 0)
            if (seteuid(0))
                  fatal_with_errno(EXIT_FAILURE, "getuid gave 0, but seteuid(0) failed");

      if (initgroups(pw->pw_name, pw->pw_gid) == -1)
            fatal_with_errno(EXIT_FAILURE, "initgroups");

      if (setgid(pw->pw_gid) == -1)
            fatal_with_errno(EXIT_FAILURE, "setgid");

      if (setuid(pw->pw_uid) == -1)
            fatal_with_errno(EXIT_FAILURE, "setuid");
}

/* drop down into a directory and throw away pointers to the old path */
void chroot_start(const char *path)
{
      if (chdir(path))
            fatal_with_errno(EXIT_FAILURE, "chdir(%s)", path);

      if (chroot(path))
            fatal_with_errno(EXIT_FAILURE, "chroot(%s)", path);

      if (chdir("/"))
            fatal_with_errno(EXIT_FAILURE, "chdir(/)");

      upsdebugx(1, "chrooted into %s", path);
}

/* drop off a pidfile for this process */
void writepid(const char *name)
{
      char  fn[SMALLBUF];
      FILE  *pidf;
      int   mask;

      /* use full path if present, else build filename in PIDPATH */
      if (*name == '/')
            snprintf(fn, sizeof(fn), "%s", name);
      else
            snprintf(fn, sizeof(fn), "%s/%s.pid", PIDPATH, name);

      mask = umask(022);
      pidf = fopen(fn, "w");

      if (pidf) {
            fprintf(pidf, "%d\n", (int) getpid());
            fclose(pidf);
      } else {
            upslog_with_errno(LOG_NOTICE, "writepid: fopen %s", fn);
      }

      umask(mask);
}

/* open pidfn, get the pid, then send it sig */
int sendsignalfn(const char *pidfn, int sig)
{
      char  buf[SMALLBUF];
      FILE  *pidf;
      int   pid, ret;

      pidf = fopen(pidfn, "r");
      if (!pidf) {
            upslog_with_errno(LOG_NOTICE, "fopen %s", pidfn);
            return -1;
      }

      if (fgets(buf, sizeof(buf), pidf) == NULL) {
            upslogx(LOG_NOTICE, "Failed to read pid from %s", pidfn);
            return -1;
      }     

      pid = strtol(buf, (char **)NULL, 10);

      if (pid < 2) {
            upslogx(LOG_NOTICE, "Ignoring invalid pid number %d", pid);
            return -1;
      }

      /* see if this is going to work first */
      ret = kill(pid, 0);

      if (ret < 0) {
            perror("kill");
            return -1;
      }

      /* now actually send it */
      ret = kill(pid, sig);

      if (ret < 0) {
            perror("kill");
            return -1;
      }

      return 0;
}

int snprintfcat(char *dst, size_t size, const char *fmt, ...)
{
      va_list ap;
      size_t len = strlen(dst);
      int ret;

      size--;
      assert(len <= size);

      va_start(ap, fmt);
      ret = vsnprintf(dst + len, size - len, fmt, ap);
      va_end(ap);

      dst[size] = '\0';
      return len + ret;
}

/* lazy way to send a signal if the program uses the PIDPATH */
int sendsignal(const char *progname, int sig)
{
      char  fn[SMALLBUF];

      snprintf(fn, sizeof(fn), "%s/%s.pid", PIDPATH, progname);

      return sendsignalfn(fn, sig);
}

const char *xbasename(const char *file)
{
      const char *p = strrchr(file, '/');

      if (p == NULL)
            return file;
      return p + 1;
}

static void vupslog(int priority, const char *fmt, va_list va, int use_strerror)
{
      int   ret;
      char  buf[LARGEBUF];

      ret = vsnprintf(buf, sizeof(buf), fmt, va);

      if ((ret < 0) || (ret >= (int) sizeof(buf)))
            syslog(LOG_WARNING, "vupslog: vsnprintf needed more than %d bytes",
                  LARGEBUF);

      if (use_strerror)
            snprintfcat(buf, sizeof(buf), ": %s", strerror(errno));

      if (xbit_test(upslog_flags, UPSLOG_STDERR))
            fprintf(stderr, "%s\n", buf);
      if (xbit_test(upslog_flags, UPSLOG_SYSLOG))
            syslog(priority, "%s", buf);
}

/* Return the default path for the directory containing configuration files */
const char * confpath(void) 
{
      const char * path;

      if ((path = getenv("NUT_CONFPATH")) == NULL)
            path = CONFPATH;

      return path;
}

/* Return the default path for the directory containing state files */
const char * dflt_statepath(void) 
{
      const char * path;

      if ((path = getenv("NUT_STATEPATH")) == NULL)
            path = STATEPATH;

      return path;
}

/* Return the alternate path for pid files */
const char * altpidpath(void) 
{
#ifdef ALTPIDPATH
      return ALTPIDPATH;
#else
      return dflt_statepath();
#endif
}

/* logs the formatted string to any configured logging devices + the output of strerror(errno) */
void upslog_with_errno(int priority, const char *fmt, ...)
{
      va_list va;

      va_start(va, fmt);
      vupslog(priority, fmt, va, 1);
      va_end(va);
}

/* logs the formatted string to any configured logging devices */
void upslogx(int priority, const char *fmt, ...)
{
      va_list va;

      va_start(va, fmt);
      vupslog(priority, fmt, va, 0);
      va_end(va);
}

void upsdebug_with_errno(int level, const char *fmt, ...)
{
      va_list va;
      
      if (nut_debug_level < level)
            return;

      va_start(va, fmt);
      vupslog(LOG_DEBUG, fmt, va, 1);
      va_end(va);
}

void upsdebugx(int level, const char *fmt, ...)
{
      va_list va;
      
      if (nut_debug_level < level)
            return;

      va_start(va, fmt);
      vupslog(LOG_DEBUG, fmt, va, 0);
      va_end(va);
}

/* dump message msg and len bytes from buf to upsdebugx(level) in
   hexadecimal. (This function replaces Philippe Marzouk's original
   dump_hex() function) */
void upsdebug_hex(int level, const char *msg, const void *buf, int len)
{
      char line[100];
      int n;      /* number of characters currently in line */
      int i;      /* number of bytes output from buffer */

      n = snprintf(line, sizeof(line), "%s: (%d bytes) =>", msg, len); 

      for (i = 0; i < len; i++) {

            if (n > 72) {
                  upsdebugx(level, "%s", line);
                  line[0] = 0;
            }

            n = snprintfcat(line, sizeof(line), n ? " %02x" : "%02x",
                  ((unsigned char *)buf)[i]);
      }
      upsdebugx(level, "%s", line);
}

static void vfatal(const char *fmt, va_list va, int use_strerror)
{
      if (xbit_test(upslog_flags, UPSLOG_STDERR_ON_FATAL))
            xbit_set(&upslog_flags, UPSLOG_STDERR);
      if (xbit_test(upslog_flags, UPSLOG_SYSLOG_ON_FATAL))
            xbit_set(&upslog_flags, UPSLOG_SYSLOG);

      vupslog(LOG_ERR, fmt, va, use_strerror);
}

void fatal_with_errno(int status, const char *fmt, ...)
{
      va_list va;

      va_start(va, fmt);
      vfatal(fmt, va, (errno > 0) ? 1 : 0);
      va_end(va);

      exit(status);
}

void fatalx(int status, const char *fmt, ...)
{
      va_list va;

      va_start(va, fmt);
      vfatal(fmt, va, 0);
      va_end(va);

      exit(status);
}

static const char *oom_msg = "Out of memory";

void *xmalloc(size_t size)
{
      void *p = malloc(size);

      if (p == NULL)
            fatal_with_errno(EXIT_FAILURE, "%s", oom_msg);
      return p;
}

void *xcalloc(size_t number, size_t size)
{
      void *p = calloc(number, size);

      if (p == NULL)
            fatal_with_errno(EXIT_FAILURE, "%s", oom_msg);
      return p;
}

void *xrealloc(void *ptr, size_t size)
{
      void *p = realloc(ptr, size);

      if (p == NULL)
            fatal_with_errno(EXIT_FAILURE, "%s", oom_msg);
      return p;
}

char *xstrdup(const char *string)
{
      char *p = strdup(string);

      if (p == NULL)
            fatal_with_errno(EXIT_FAILURE, "%s", oom_msg);
      return p;
}

/* modify in - strip all trailing instances of <sep> */
char *rtrim(char *in, const char sep)
{
      char  *p;

      p = &in[strlen(in) - 1];

      while ((p >= in) && (*p == sep))
            *p-- = '\0';
      
      return in;
}

/* Read up to buflen bytes from fd and return the number of bytes
   read. If no data is available within d_sec + d_usec, return 0.
   On error, a value < 0 is returned (errno indicates error). */
int select_read(const int fd, void *buf, const size_t buflen, const long d_sec, const long d_usec)
{
      int         ret;
      fd_set            fds;
      struct timeval    tv;

      FD_ZERO(&fds);
      FD_SET(fd, &fds);

      tv.tv_sec = d_sec;
      tv.tv_usec = d_usec;

      ret = select(fd + 1, &fds, NULL, NULL, &tv);

      if (ret < 1) {
            return ret;
      }

      return read(fd, buf, buflen);
}

/* Write up to buflen bytes to fd and return the number of bytes
   written. If no data is available within d_sec + d_usec, return 0.
   On error, a value < 0 is returned (errno indicates error). */
int select_write(const int fd, const void *buf, const size_t buflen, const long d_sec, const long d_usec)
{
      int         ret;
      fd_set            fds;
      struct timeval    tv;

      FD_ZERO(&fds);
      FD_SET(fd, &fds);

      tv.tv_sec = d_sec;
      tv.tv_usec = d_usec;

      ret = select(fd + 1, NULL, &fds, NULL, &tv);

      if (ret < 1) {
            return ret;
      }

      return write(fd, buf, buflen);
}

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