ExecCommandList

/* License: GPL */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <libgen.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>

const char * basename_argv0;

int ExecCommandWaitChild(pid_t ChildPID) {
  int ChildStatus;
  int status;
  status=waitpid(ChildPID,&ChildStatus,0);
  if (status==-1)
    return (-1);
  if (WIFEXITED(ChildStatus))
    return (WEXITSTATUS(ChildStatus));
  else
    return (-1);
}

int ExecCommandWaitChildList(pid_t * ChildPIDList) {
  int ExitStatus;
  ExitStatus=0;
  if (ChildPIDList!=NULL) {
    unsigned int ChildCount;
    int i;
    ChildCount=0;
    for (i=0; ChildPIDList[i]!=-1; i++)
      ChildCount++;
    for (i=ChildCount-1; i>=0; i--) {
      int ChildExitStatus;
      ChildExitStatus=ExecCommandWaitChild(ChildPIDList[i]);
      if (ExitStatus==0 && ChildExitStatus!=0)
    ExitStatus=ChildExitStatus;
    }
    free(ChildPIDList);
  }
  return (ExitStatus);
}

int ExecCommandListRedir(const char * const * const * const CommandArgList, char * const FileName) {
  const char * const * CommandArgs;
  int * PipeFDList;
  pid_t * ChildPIDList;
  unsigned int ChildCount;
  int OutFileFD;
  int ExitStatus;
  bool ForegroundProcess;
  long int maxfd;
  int SavedErrNo;
  int status;
  int i;
  if (CommandArgList==NULL)
    return (-1);
  ChildCount=0;
  for (i=0; CommandArgList[i]!=NULL; i++)
    ChildCount++;
  if (ChildCount==0)
    return (-1);
#ifdef DEBUG
  int j;
  fprintf(stderr,"%s: ",__FUNCTION__);
  for (i=0; i<ChildCount; i++) {
    for (j=0; CommandArgList[i][j]!=NULL; j++)
      fprintf(stderr,"%s ",CommandArgList[i][j]);
    if (i<ChildCount-1)
      fprintf(stderr,"| ");
    else
      fprintf(stderr,"> %s\n",FileName);
  }
#endif
  PipeFDList=NULL;
  ChildPIDList=NULL;
  ExitStatus=-1;
  if (FileName!=NULL) {
    OutFileFD=mkstemp(FileName);
    if (OutFileFD==-1)
      goto ExecCommandListRedirExit;
    ForegroundProcess=false;
  }
  else {
    OutFileFD=-1;
    ForegroundProcess=true;
  }
  if (ChildCount>1) {
    PipeFDList=malloc((ChildCount-1)*(2*sizeof(int)));
    if (PipeFDList==NULL)
      goto ExecCommandListRedirExit;
    for (i=0; i<ChildCount-1; i++) {
      PipeFDList[2*i+0]=-1;
      PipeFDList[2*i+1]=-1;
    }
  }
  ChildPIDList=malloc((ChildCount+1)*sizeof(pid_t));
  if (ChildPIDList==NULL)
    goto ExecCommandListRedirExit;
  for (i=0; i<ChildCount+1; i++)
    ChildPIDList[i]=-1;
  maxfd=sysconf(_SC_OPEN_MAX);
  for (i=ChildCount-1; i>=0; i--) {
    if (i>0) {
      status=pipe(&PipeFDList[2*(i-1)]);
      if (status==-1) {
    if (ForegroundProcess==true)
      fprintf(stderr,"%s: pipe creation failed: %s\n",basename_argv0,strerror(errno));
    goto ExecCommandListRedirExit;
      }
    }
    ChildPIDList[i]=fork();
    if (ChildPIDList[i]==0) { /* child */
      struct sigaction sa;
      int fd;
      if (i>0)
    dup2(PipeFDList[2*(i-1)+0],STDIN_FILENO);
      else if (ForegroundProcess==false) {
    fd=open("/dev/null",O_RDONLY);
    if (fd!=-1)
      dup2(fd,STDIN_FILENO);
      }
      if (i<ChildCount-1)
    dup2(PipeFDList[2*i+1],STDOUT_FILENO);
      else if (OutFileFD!=-1)
    dup2(OutFileFD,STDOUT_FILENO);
      for (fd=STDERR_FILENO+1; fd<maxfd; fd++)
    close(fd);
      CommandArgs=CommandArgList[i];
      sa.sa_handler=SIG_DFL;
      sigfillset(&sa.sa_mask);
      sa.sa_flags=0;
      sigaction(SIGINT,&sa,NULL);
      sigaction(SIGTERM,&sa,NULL);
      sigaction(SIGQUIT,&sa,NULL);
      sigaction(SIGPIPE,&sa,NULL);
      execvp(CommandArgs[0],(char * const *)CommandArgs);
      if (ForegroundProcess==true)
    fprintf(stderr,"%s: %s: %s\n",basename_argv0,CommandArgs[0],strerror(errno));
      _exit(127);
    }
    /* parent */
    else if (ChildPIDList[i]==-1) {
      if (ForegroundProcess==true)
    fprintf(stderr,"%s: fork failed: %s\n",basename_argv0,strerror(errno));
      goto ExecCommandListRedirExit;
    }
  }
  ExitStatus=0;
ExecCommandListRedirExit:
  SavedErrNo=errno;
  if (OutFileFD!=-1)
    close(OutFileFD);
  if (PipeFDList!=NULL) {
    for (i=0; i<ChildCount-1; i++) {
      close(PipeFDList[2*i+0]);
      close(PipeFDList[2*i+1]);
    }
    free(PipeFDList);
  }
  ExitStatus=ExecCommandWaitChildList(ChildPIDList);
  errno=SavedErrNo;
  return (ExitStatus);
}

FILE * ExecCommandListPipe(const char * const * const * const CommandArgList, pid_t ** ChildPIDListPtr) {
  const char * const * CommandArgs;
  int * PipeFDList;
  pid_t * ChildPIDList;
  unsigned int ChildCount;
  FILE * OutFile;
  long int maxfd;
  int SavedErrNo;
  int status;
  int i;
  *ChildPIDListPtr=NULL;
  if (CommandArgList==NULL)
    return (NULL);
  ChildCount=0;
  for (i=0; CommandArgList[i]!=NULL; i++)
    ChildCount++;
  if (ChildCount==0)
    return (NULL);
#ifdef DEBUG
  int j;
  fprintf(stderr,"%s: ",__FUNCTION__);
  for (i=0; i<ChildCount; i++) {
    for (j=0; CommandArgList[i][j]!=NULL; j++)
      fprintf(stderr,"%s ",CommandArgList[i][j]);
    if (i<ChildCount-1)
      fprintf(stderr,"| ");
    else
      fprintf(stderr,"| %s\n",basename_argv0);
  }
#endif
  OutFile=NULL;
  PipeFDList=malloc(ChildCount*(2*sizeof(int)));
  if (PipeFDList==NULL)
    goto ExecCommandListPipeExit;
  for (i=0; i<ChildCount; i++) {
    PipeFDList[2*i+0]=-1;
    PipeFDList[2*i+1]=-1;
  }
  ChildPIDList=malloc((ChildCount+1)*sizeof(pid_t));
  if (ChildPIDList==NULL)
    goto ExecCommandListPipeExit;
  for (i=0; i<ChildCount+1; i++)
    ChildPIDList[i]=-1;
  *ChildPIDListPtr=ChildPIDList;
  status=pipe(&PipeFDList[2*(ChildCount-1)]);
  if (status==-1)
    goto ExecCommandListPipeExit;
  maxfd=sysconf(_SC_OPEN_MAX);
  for (i=ChildCount-1; i>=0; i--) {
    if (i>0) {
      status=pipe(&PipeFDList[2*(i-1)]);
      if (status==-1)
    goto ExecCommandListPipeExit;
    }
    ChildPIDList[i]=fork();
    if (ChildPIDList[i]==0) { /* child */
      struct sigaction sa;
      int fd;
      if (i>0)
    dup2(PipeFDList[2*(i-1)+0],STDIN_FILENO);
      else {
    fd=open("/dev/null",O_RDONLY);
    if (fd!=-1)
      dup2(fd,STDIN_FILENO);
      }
      dup2(PipeFDList[2*i+1],STDOUT_FILENO);
      for (fd=STDERR_FILENO+1; fd<maxfd; fd++)
    close(fd);
      CommandArgs=CommandArgList[i];
      sa.sa_handler=SIG_DFL;
      sigfillset(&sa.sa_mask);
      sa.sa_flags=0;
      sigaction(SIGINT,&sa,NULL);
      sigaction(SIGTERM,&sa,NULL);
      sigaction(SIGQUIT,&sa,NULL);
      sigaction(SIGPIPE,&sa,NULL);
      execvp(CommandArgs[0],(char * const *)CommandArgs);
      _exit(127);
    }
    /* parent */
    else if (ChildPIDList[i]==-1)
      goto ExecCommandListPipeExit;
  }
  OutFile=fdopen(PipeFDList[2*(ChildCount-1)+0],"r");
ExecCommandListPipeExit:
  SavedErrNo=errno;
  if (PipeFDList!=NULL) {
    for (i=0; i<ChildCount-1; i++) {
      close(PipeFDList[2*i+0]);
      close(PipeFDList[2*i+1]);
    }
    if (OutFile==NULL)
      close(PipeFDList[2*(ChildCount-1)+0]);
    close(PipeFDList[2*(ChildCount-1)+1]);
    free(PipeFDList);
  }
  errno=SavedErrNo;
  return (OutFile);
}

int ExecCommandRedir(const char * const * const CommandArgs, char * const FileName) {
  const char * const * CommandArgList[2];
  CommandArgList[0]=CommandArgs;
  CommandArgList[1]=NULL;
  return (ExecCommandListRedir(CommandArgList,FileName));
}

FILE * ExecCommandPipe(const char * const * const CommandArgs, pid_t * ChildPID) {
  const char * const * CommandArgList[2];
  pid_t * ChildPIDList;
  FILE * OutFile;
  int SavedErrNo;
  CommandArgList[0]=CommandArgs;
  CommandArgList[1]=NULL;
  OutFile=ExecCommandListPipe(CommandArgList,&ChildPIDList);
  SavedErrNo=errno;
  *ChildPID=ChildPIDList[0];
  errno=SavedErrNo;
  return (OutFile);
}

int ExecCommand(const char * const * CommandArgs) {
  int status;
  if (CommandArgs==NULL)
    return (-1);
  status=ExecCommandRedir(CommandArgs,NULL);
  return (status);
}

int main(int argc, char * const argv[]) {
  static const char * const Command1Args[]={
    "ls",
    "-l",
    "--si",
    "--color=auto",
    "--show-control-chars",
    "/",
    NULL
  };
  static const char * const Command2Args[]={
    "grep",
    "-i",
    "Jan",
    NULL
  };
  static const char * const Command3Args[]={
    "head",
    "-n",
    "3",
    NULL
  };
  static const char * const * const CommandArgList[]={
    Command1Args,
    Command2Args,
    Command3Args,
    NULL
  };
  FILE * infile;
  pid_t * ChildPIDList;
  pid_t ChildPID;
  int ExitStatus;
  basename_argv0=basename(argv[0]);

  /* ls -l --si --color=auto --show-control-chars / | grep -i Jan | head -n 3 | exec */

  infile=ExecCommandListPipe(CommandArgList,&ChildPIDList);
  if (infile==NULL) {
    fprintf(stderr,"%s: ExecCommandListPipe: %s\n",basename_argv0,strerror(errno));
    ExitStatus=ExecCommandWaitChildList(ChildPIDList);
    return (ExitStatus);
  }
  while (!feof(infile)) {
    char Buffer[1024];
    char * ptr;
    ptr=fgets(Buffer,sizeof(Buffer),infile);
    if (ptr==NULL) {
      if (feof(infile))
    break;
      else {
    fclose(infile);
    return (2);
      }
    }
    fputs(Buffer,stdout);
  }
  fclose(infile);
  ExitStatus=ExecCommandWaitChildList(ChildPIDList);
  fprintf(stderr,"%s: pipeline exit status: %d\n",basename_argv0,ExitStatus);

  /* ls -l --si --color=auto --show-control-chars / | exec */

  infile=ExecCommandPipe(Command1Args,&ChildPID);
  if (infile==NULL) {
    fprintf(stderr,"%s: ExecCommandPipe: %s\n",basename_argv0,strerror(errno));
    ExitStatus=ExecCommandWaitChild(ChildPID);
    return (ExitStatus);
  }
  while (!feof(infile)) {
    char Buffer[1024];
    char * ptr;
    ptr=fgets(Buffer,sizeof(Buffer),infile);
    if (ptr==NULL) {
      if (feof(infile))
    break;
      else {
    fclose(infile);
    return (2);
      }
    }
    fputs(Buffer,stdout);
  }
  fclose(infile);
  ExitStatus=ExecCommandWaitChild(ChildPID);
  fprintf(stderr,"%s: command exit status: %d\n",basename_argv0,ExitStatus);

  return (0);
}