serdo.c

#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <ctype.h>
#include <sys/wait.h>
#include <sys/resource.h>

#include <libowfat/str.h>
#include <libowfat/byte.h>
#include <libowfat/scan.h>
#include <libowfat/errmsg.h>

#define MAXENV 256
char* envp[MAXENV+2];
int envc;

int continueonerror;

int envset(char* s) {
  int i,l;
  if (s[l=str_chr(s,'=')]!='=') return -1;
  ++l;
  for (i=0; i<envc; ++i)
    if (byte_equal(envp[i],l,s)) {
      envp[i]=s;
      return 0;
    }
  if (envc<MAXENV) {
    envp[envc]=s;
    envp[++envc]=0;
    return 0;
  }
  return -1;
}

int spawn(char** argv, int last) {
  int i,ignore;
  ignore=(argv[0][0]=='-');
  if (ignore) ++argv[0];
  if (str_equal(argv[0],"cd")) {
    if (chdir(argv[1])==-1) {
      carpsys("chdir failed");
failornot:
      return ignore?0:-1;
    }
    return 0;
  } else if (str_equal(argv[0],"export")) {
    for (i=1; argv[i]; ++i) envset(argv[i]);
    return 0;
  } else if (str_equal(argv[0],"ulimit")) {
    struct rlimit rl;
    for (i=1; argv[i] && argv[i+1]; i+=2) {
      int id=-1;
      if (argv[i][0]!='-') {
ulimitsyntax:
	carp("ulimit syntax error: ",argv[i]);
	continue;
      }
      switch(argv[i][1]) {
	case 'c': id=RLIMIT_CORE; break;
	case 'd': id=RLIMIT_DATA; break;
	case 'e': id=RLIMIT_NICE; break;
	case 'f': id=RLIMIT_FSIZE; break;
	case 'i': id=RLIMIT_SIGPENDING; break;
	case 'l': id=RLIMIT_MEMLOCK; break;
	case 'm': id=RLIMIT_RSS; break;
	case 'n': id=RLIMIT_NOFILE; break;
	case 'r': id=RLIMIT_RTPRIO; break;
	case 's': id=RLIMIT_STACK; break;
	case 't': id=RLIMIT_CPU; break;
	case 'u': id=RLIMIT_NPROC; break;
	case 'v': id=RLIMIT_AS; break;
	case 'x': id=RLIMIT_LOCKS; break;
	default: goto ulimitsyntax;
      }
      if (!strcmp(argv[i+1],"unlimited")) {
	rl.rlim_cur=rl.rlim_max=RLIM_INFINITY;
      } else {
	unsigned long ul;
	if (argv[i+1][scan_ulong(argv[i+1],&ul)])
	  goto ulimitsyntax;
	rl.rlim_cur=rl.rlim_max=ul;
      }
      if (setrlimit(id,&rl)==-1) {
	carpsys("ulimit failed");
	goto failornot;
      }
    }
    return 0;
  }
  if (!last) {
    if ((i=fork())==-1) diesys(1,"cannot fork");
  } else i=0;
  if (!i) {
    /* child */
    environ=envp;
    _exit(execvp(argv[0],argv));
  }
  if (waitpid(i,&i,0)==-1) diesys(1,"waitpid failed");
  if (ignore) return 0;
  if (!WIFEXITED(i))
    return -1;
  return WEXITSTATUS(i);
}

int run(char* s,int last) {
  int i,spaces;
  char** argv,**next;
  for (i=spaces=0; s[i]; ++i) if (s[i]==' ') ++spaces;
  next=argv=alloca((spaces+2)*sizeof(char*));

  while (*s) {
    while (*s && isspace(*s)) ++s;
    if (*s=='"') {
      ++s;
      *next=s;
      while (*s && (*s != '"' || s[-1] == '\\')) ++s;
      if (!*s) {
	--*next;
	break;
      }
      *s=0;
      ++s;
    } else if (*s=='\'') {
      ++s;
      *next=s;
      while (*s && (*s != '\'' || s[-1] == '\\')) ++s;
      if (!*s) {
	--*next;
	break;
      }
      *s=0;
      ++s;
    } else {
      *next=s;
      while (*s && *s!=' ' && *s!='\t') ++s;
      if (*s) {
	*s=0;
	++s;
      }
    }
    ++next;
  }
  *next=0;

  return spawn(argv,last);
}

int execute(char* s) {
  char* start;
  int r;
  r=0;
  while (*s) {
    int last;
    while (isspace(*s)) ++s;
    if (*s == '#') {
      while (*s && *s != '\n') ++s;
      continue;
    }
    start=s;

    while (*s && *s != '\n') ++s;
    /* advance to the end of the line */
    if (*s) {
      /* not the last line in the file */
      char* tmp;
      *s=0;
      ++s;
      /* If it's the last command in the file, we do not fork+exec but
       * we execve it directly.  So we need to find out here if this is
       * the last command in the file.  For that we need to skip all the
       * lines after it that are comments */
      for (tmp=s; *tmp; ++tmp)
	if (!isspace(*tmp) && *tmp=='#') {
	  for (++tmp; *tmp && *tmp!='\n'; ++tmp) ;
	} else
	  break;
      last=(*tmp==0);
    } else
      last=1;
    r=run(start,last);
    if (r!=0 && !continueonerror)
      break;
  }
  return r;
}

int batch(char* s) {
  struct stat ss;
  int fd=open(s,O_RDONLY);
  char* map;
  if (fd==-1) diesys(1,"could not open ",s);
  if (fstat(fd,&ss)==-1) diesys(1,"could not stat ",s);
  if (ss.st_size>32768) die(1,"file ",s," is too large");
  map=alloca(ss.st_size+1);
  if (read(fd,map,ss.st_size)!=(long)ss.st_size) diesys(1,"read error");
  map[ss.st_size]=0;
  close(fd);

  return execute(map);
}

int main(int argc,char* argv[],char* env[]) {
  static char* fakeargv[]={0,"script",0};
  int r;
  (void)argc;
  if (argc<2) {
    if (!access("script",O_RDONLY))
      argv=fakeargv;
    else
      die(1,"usage: serdo [-c] filename");
  }
  errmsg_iam("serdo");
  for (envc=0; envc<MAXENV && env[envc]; ++envc) envp[envc]=env[envc];
  envp[envc]=0;
  if (str_equal(argv[1],"-c")) {
    continueonerror=1;
    ++argv;
  }
  while (*++argv) {
    if ((r=batch(*argv)))
      return r;
  }
  return 0;
}