Final (I think) version of xargs. Throw away all that tedious string
authorEric Andersen <andersen@codepoet.org>
Mon, 25 Sep 2000 20:23:21 +0000 (20:23 -0000)
committerEric Andersen <andersen@codepoet.org>
Mon, 25 Sep 2000 20:23:21 +0000 (20:23 -0000)
scrubbing, and quit using system.  Instead, use fork() and exec(), which
yields and smaller, simpler, and cleaner design.
 -Erik

findutils/xargs.c
xargs.c

index 21bfb6b..b8ac31a 100644 (file)
 #include <errno.h>
 #include <getopt.h>
 #include <ctype.h>
-
-/* get_sh_safe_line_from_file() - This function reads an entire line from a text file
- * up to a newline. It returns a malloc'ed char * which must be stored and
- * free'ed  by the caller. */
-extern char *get_sh_safe_line_from_file(FILE *file)
-{
-       static const int GROWBY = 80; /* how large we will grow strings by */
-
-       char ch, last_ch = 0;
-       char tmp[]=" ";
-       int idx = 0;
-       char *linebuf = NULL;
-       int linebufsz = 0;
-
-       while (1) {
-               ch = fgetc(file);
-               if (ch == EOF)
-                       break;
-               
-               /* grow the line buffer as necessary */
-               while (idx > linebufsz-4)
-                       linebuf = xrealloc(linebuf, linebufsz += GROWBY);
-
-               /* Remove any extra spaces */
-               if (last_ch == ' ' && ch == ' ')
-                       continue;
-
-               /* Replace any tabs with spaces */
-               if (ch == '\t')
-                       ch=' ';
-
-               /* Escape any characters that are treated specially by /bin/sh */
-               *tmp=ch;
-               if (strpbrk(tmp, "\\~`!$^&*()=|{}[];\"'<>?#") != NULL && last_ch!='\\') {
-                       linebuf[idx++] = '\\';
-               }
-
-               linebuf[idx++] = ch;
-               last_ch=ch;
-
-               if (ch == '\n')
-                       break;
-       }
-       if (idx == 0 && last_ch!=0)
-               linebuf[idx++]=' ';
-
-       if (idx == 0)
-               return NULL;
-
-       linebuf[idx] = 0;
-       return linebuf;
-}
-
+#include <sys/types.h>
+#include <sys/wait.h>
 
 
 int xargs_main(int argc, char **argv)
 {
        char *in_from_stdin = NULL;
-       char *args_from_cmdline = NULL;
+       char *args = NULL;
        char *cmd_to_be_executed = NULL;
        char traceflag = 0;
-       int len_args_from_cmdline, len_cmd_to_be_executed, len, opt;
+       int len_args=10, len_cmd_to_be_executed, opt;
+       pid_t pid;
+       int wpid, status;
 
        /* Note that we do not use getopt here, since
         * we only want to interpret initial options,
@@ -102,50 +53,45 @@ int xargs_main(int argc, char **argv)
                                        break;
                                default:
                                        fatalError(xargs_usage);
-                               }
+                       }
                }
        }
 
-       /* Store the command and arguments to be executed (from the command line) */
+       /* Store the command to be executed (taken from the command line) */
        if (argc == 0) {
-               len_args_from_cmdline = 6;
-               args_from_cmdline = xmalloc(len_args_from_cmdline);
-               strcat(args_from_cmdline, "echo ");
+               len_cmd_to_be_executed=6;
+               cmd_to_be_executed = xmalloc(len_cmd_to_be_executed);
+               strcat(cmd_to_be_executed, "echo");
        } else {
                opt=strlen(*argv);
-               len_args_from_cmdline = (opt > 10)? opt : 10;
-               args_from_cmdline = xcalloc(len_args_from_cmdline, sizeof(char));
-               while (argc-- > 0) {
-                       if (strlen(*argv) + strlen(args_from_cmdline) >
-                               len_args_from_cmdline) {
-                               len_args_from_cmdline += strlen(*argv);
-                               args_from_cmdline =
-                                       xrealloc(args_from_cmdline,
-                                                        len_args_from_cmdline+1);
-                       }
-                       strcat(args_from_cmdline, *argv);
-                       strcat(args_from_cmdline, " ");
-                       ++argv;
-               }
+               len_cmd_to_be_executed = (opt > 10)? opt : 10;
+               cmd_to_be_executed = xcalloc(len_cmd_to_be_executed, sizeof(char));
+               strcat(cmd_to_be_executed, *argv);
        }
 
-       /* Set up some space for the command to be executed to be held in */
-       len_cmd_to_be_executed=10;
-       cmd_to_be_executed = xcalloc(len_cmd_to_be_executed, sizeof(char));
-       strcpy(cmd_to_be_executed, args_from_cmdline);
 
-       /* Now, read in one line at a time from stdin, and run command+args on it */
-       in_from_stdin = get_sh_safe_line_from_file(stdin);
+       /* Now, read in one line at a time from stdin, and stroe this to be used later 
+        * as an argument to the command we just stored */
+       in_from_stdin = get_line_from_file(stdin);
        for (;in_from_stdin!=NULL;) {
                char *tmp;
                opt = strlen(in_from_stdin);
-               len = opt + len_args_from_cmdline;
-               len_cmd_to_be_executed+=len+3;
-               cmd_to_be_executed=xrealloc(cmd_to_be_executed, len_cmd_to_be_executed);
+               len_args += opt + 3;
+               args=xrealloc(args, len_args);
 
                /* Strip out the final \n */
                in_from_stdin[opt-1]=' ';
-                       
+
+               /* Replace any tabs with spaces */
+               while( (tmp = strchr(in_from_stdin, '\t')) != NULL )
+                       *tmp=' ';
+
+               /* Strip out any extra intra-word spaces */
+               while( (tmp = strstr(in_from_stdin, "  ")) != NULL ) {
+                       opt = strlen(in_from_stdin);
+                       memmove(tmp, tmp+1, opt-(tmp-in_from_stdin));
+               }
+
                /* trim trailing whitespace */
                opt = strlen(in_from_stdin) - 1;
                while (isspace(in_from_stdin[opt]))
@@ -157,26 +103,49 @@ int xargs_main(int argc, char **argv)
                while(isspace(*tmp))
                        tmp++;
 
-               strcat(cmd_to_be_executed, tmp);
-               strcat(cmd_to_be_executed, " ");
-       
+               strcat(args, tmp);
+               strcat(args, " ");
+
                free(in_from_stdin);
-               in_from_stdin = get_sh_safe_line_from_file(stdin);
+               in_from_stdin = get_line_from_file(stdin);
        }
 
-       if (traceflag==1)
+       if (traceflag==1) {
                fputs(cmd_to_be_executed, stderr);
+               fputs(args, stderr);
+       }
 
-       if ((system(cmd_to_be_executed) != 0) && (errno != 0))
-               fatalError("%s", strerror(errno));
+       if ((pid = fork()) == 0) {
+               char *cmd[255];
+               int i=1;
+
+               //printf("argv[0]='%s'\n", cmd_to_be_executed);
+               cmd[0] = cmd_to_be_executed;
+               while (--argc && ++argv && *argv ) {
+                       //printf("argv[%d]='%s'\n", i, *argv);
+                       cmd[i++]=*argv;
+               }
+               //printf("argv[%d]='%s'\n", i, args);
+               cmd[i++] = args;
+               cmd[i] = NULL;
+               execvp(cmd_to_be_executed, cmd);
+
+               /* What?  Still here?  Exit with an error */
+               fatalError("%s: %s\n", cmd_to_be_executed, strerror(errno));
+       }
+       /* Wait for a child process to exit */
+       wpid = wait(&status);
 
 
 #ifdef BB_FEATURE_CLEAN_UP
-       free(args_from_cmdline);
+       free(args);
        free(cmd_to_be_executed);
 #endif
 
-       return 0;
+       if (wpid > 0)
+               return (WEXITSTATUS(status));
+       else 
+               return EXIT_FAILURE;
 }
 /*
 Local Variables:
@@ -185,4 +154,3 @@ c-basic-offset: 4
 tab-width: 4
 End:
 */
-
diff --git a/xargs.c b/xargs.c
index 21bfb6b..b8ac31a 100644 (file)
--- a/xargs.c
+++ b/xargs.c
 #include <errno.h>
 #include <getopt.h>
 #include <ctype.h>
-
-/* get_sh_safe_line_from_file() - This function reads an entire line from a text file
- * up to a newline. It returns a malloc'ed char * which must be stored and
- * free'ed  by the caller. */
-extern char *get_sh_safe_line_from_file(FILE *file)
-{
-       static const int GROWBY = 80; /* how large we will grow strings by */
-
-       char ch, last_ch = 0;
-       char tmp[]=" ";
-       int idx = 0;
-       char *linebuf = NULL;
-       int linebufsz = 0;
-
-       while (1) {
-               ch = fgetc(file);
-               if (ch == EOF)
-                       break;
-               
-               /* grow the line buffer as necessary */
-               while (idx > linebufsz-4)
-                       linebuf = xrealloc(linebuf, linebufsz += GROWBY);
-
-               /* Remove any extra spaces */
-               if (last_ch == ' ' && ch == ' ')
-                       continue;
-
-               /* Replace any tabs with spaces */
-               if (ch == '\t')
-                       ch=' ';
-
-               /* Escape any characters that are treated specially by /bin/sh */
-               *tmp=ch;
-               if (strpbrk(tmp, "\\~`!$^&*()=|{}[];\"'<>?#") != NULL && last_ch!='\\') {
-                       linebuf[idx++] = '\\';
-               }
-
-               linebuf[idx++] = ch;
-               last_ch=ch;
-
-               if (ch == '\n')
-                       break;
-       }
-       if (idx == 0 && last_ch!=0)
-               linebuf[idx++]=' ';
-
-       if (idx == 0)
-               return NULL;
-
-       linebuf[idx] = 0;
-       return linebuf;
-}
-
+#include <sys/types.h>
+#include <sys/wait.h>
 
 
 int xargs_main(int argc, char **argv)
 {
        char *in_from_stdin = NULL;
-       char *args_from_cmdline = NULL;
+       char *args = NULL;
        char *cmd_to_be_executed = NULL;
        char traceflag = 0;
-       int len_args_from_cmdline, len_cmd_to_be_executed, len, opt;
+       int len_args=10, len_cmd_to_be_executed, opt;
+       pid_t pid;
+       int wpid, status;
 
        /* Note that we do not use getopt here, since
         * we only want to interpret initial options,
@@ -102,50 +53,45 @@ int xargs_main(int argc, char **argv)
                                        break;
                                default:
                                        fatalError(xargs_usage);
-                               }
+                       }
                }
        }
 
-       /* Store the command and arguments to be executed (from the command line) */
+       /* Store the command to be executed (taken from the command line) */
        if (argc == 0) {
-               len_args_from_cmdline = 6;
-               args_from_cmdline = xmalloc(len_args_from_cmdline);
-               strcat(args_from_cmdline, "echo ");
+               len_cmd_to_be_executed=6;
+               cmd_to_be_executed = xmalloc(len_cmd_to_be_executed);
+               strcat(cmd_to_be_executed, "echo");
        } else {
                opt=strlen(*argv);
-               len_args_from_cmdline = (opt > 10)? opt : 10;
-               args_from_cmdline = xcalloc(len_args_from_cmdline, sizeof(char));
-               while (argc-- > 0) {
-                       if (strlen(*argv) + strlen(args_from_cmdline) >
-                               len_args_from_cmdline) {
-                               len_args_from_cmdline += strlen(*argv);
-                               args_from_cmdline =
-                                       xrealloc(args_from_cmdline,
-                                                        len_args_from_cmdline+1);
-                       }
-                       strcat(args_from_cmdline, *argv);
-                       strcat(args_from_cmdline, " ");
-                       ++argv;
-               }
+               len_cmd_to_be_executed = (opt > 10)? opt : 10;
+               cmd_to_be_executed = xcalloc(len_cmd_to_be_executed, sizeof(char));
+               strcat(cmd_to_be_executed, *argv);
        }
 
-       /* Set up some space for the command to be executed to be held in */
-       len_cmd_to_be_executed=10;
-       cmd_to_be_executed = xcalloc(len_cmd_to_be_executed, sizeof(char));
-       strcpy(cmd_to_be_executed, args_from_cmdline);
 
-       /* Now, read in one line at a time from stdin, and run command+args on it */
-       in_from_stdin = get_sh_safe_line_from_file(stdin);
+       /* Now, read in one line at a time from stdin, and stroe this to be used later 
+        * as an argument to the command we just stored */
+       in_from_stdin = get_line_from_file(stdin);
        for (;in_from_stdin!=NULL;) {
                char *tmp;
                opt = strlen(in_from_stdin);
-               len = opt + len_args_from_cmdline;
-               len_cmd_to_be_executed+=len+3;
-               cmd_to_be_executed=xrealloc(cmd_to_be_executed, len_cmd_to_be_executed);
+               len_args += opt + 3;
+               args=xrealloc(args, len_args);
 
                /* Strip out the final \n */
                in_from_stdin[opt-1]=' ';
-                       
+
+               /* Replace any tabs with spaces */
+               while( (tmp = strchr(in_from_stdin, '\t')) != NULL )
+                       *tmp=' ';
+
+               /* Strip out any extra intra-word spaces */
+               while( (tmp = strstr(in_from_stdin, "  ")) != NULL ) {
+                       opt = strlen(in_from_stdin);
+                       memmove(tmp, tmp+1, opt-(tmp-in_from_stdin));
+               }
+
                /* trim trailing whitespace */
                opt = strlen(in_from_stdin) - 1;
                while (isspace(in_from_stdin[opt]))
@@ -157,26 +103,49 @@ int xargs_main(int argc, char **argv)
                while(isspace(*tmp))
                        tmp++;
 
-               strcat(cmd_to_be_executed, tmp);
-               strcat(cmd_to_be_executed, " ");
-       
+               strcat(args, tmp);
+               strcat(args, " ");
+
                free(in_from_stdin);
-               in_from_stdin = get_sh_safe_line_from_file(stdin);
+               in_from_stdin = get_line_from_file(stdin);
        }
 
-       if (traceflag==1)
+       if (traceflag==1) {
                fputs(cmd_to_be_executed, stderr);
+               fputs(args, stderr);
+       }
 
-       if ((system(cmd_to_be_executed) != 0) && (errno != 0))
-               fatalError("%s", strerror(errno));
+       if ((pid = fork()) == 0) {
+               char *cmd[255];
+               int i=1;
+
+               //printf("argv[0]='%s'\n", cmd_to_be_executed);
+               cmd[0] = cmd_to_be_executed;
+               while (--argc && ++argv && *argv ) {
+                       //printf("argv[%d]='%s'\n", i, *argv);
+                       cmd[i++]=*argv;
+               }
+               //printf("argv[%d]='%s'\n", i, args);
+               cmd[i++] = args;
+               cmd[i] = NULL;
+               execvp(cmd_to_be_executed, cmd);
+
+               /* What?  Still here?  Exit with an error */
+               fatalError("%s: %s\n", cmd_to_be_executed, strerror(errno));
+       }
+       /* Wait for a child process to exit */
+       wpid = wait(&status);
 
 
 #ifdef BB_FEATURE_CLEAN_UP
-       free(args_from_cmdline);
+       free(args);
        free(cmd_to_be_executed);
 #endif
 
-       return 0;
+       if (wpid > 0)
+               return (WEXITSTATUS(status));
+       else 
+               return EXIT_FAILURE;
 }
 /*
 Local Variables:
@@ -185,4 +154,3 @@ c-basic-offset: 4
 tab-width: 4
 End:
 */
-