execl(3) and its variants use a sentinel to terminate the variadic argument list, in the form of a null pointer constant of type pointer to char. POSIX mandates that NULL is a null pointer constant of type pointer to void, which is not of an equivalent type to that required by execl(3) and its variants, resulting in undefined behaviour. This commit casts all such instances of NULL to pointer to char type. For consistency, it also adds const-qualification to any such instances which had already been casted, and were not const-qualified.
115 lines
2.7 KiB
C
115 lines
2.7 KiB
C
/*
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* Copyright (c) 2012, 2013 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* help.c
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* Prints a friendly message and print the names of everything in PATH.
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*/
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <dirent.h>
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#include <errno.h>
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#include <error.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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int main(void)
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{
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printf("Please enter the name of one of the following programs:\n");
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const char* path = getenv("PATH");
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if ( !path )
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return 0;
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pid_t child_pid = -1;
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if ( isatty(1) )
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{
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int pipe_fds[2];
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if ( pipe(pipe_fds) )
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error(1, errno, "pipe");
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if ( (child_pid = fork()) < 0 )
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error(1, errno, "fork");
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if ( !child_pid )
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{
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dup2(pipe_fds[0], 0);
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close(pipe_fds[0]);
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close(pipe_fds[1]);
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execlp("column", "column", (const char*) NULL);
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execlp("cat", "cat", (const char*) NULL);
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int ic;
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while ( (ic = fgetc(stdin)) != EOF )
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fputc(ic, stdout);
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exit(0);
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}
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dup2(pipe_fds[1], 1);
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close(pipe_fds[0]);
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close(pipe_fds[1]);
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}
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char* dirname = NULL;
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while ( *path )
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{
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if ( dirname ) { free(dirname); dirname = NULL; }
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size_t len = strcspn(path, ":");
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if ( !len ) { path++; continue; }
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dirname = (char*) malloc((len+1) * sizeof(char));
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if ( !dirname )
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error(1, errno, "malloc");
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memcpy(dirname, path, len * sizeof(char));
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dirname[len] = '\0';
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path += len + 1;
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DIR* dir = opendir(dirname);
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if ( !dir )
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continue;
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struct dirent* entry;
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while ( (entry = readdir(dir)) )
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{
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if ( entry->d_name[0] == '.' )
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continue;
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struct stat st;
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if ( fstatat(dirfd(dir), entry->d_name, &st, 0) )
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continue;
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if ( !S_ISREG(st.st_mode) )
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continue;
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if ( !(st.st_mode & 0111) )
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continue;
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printf("%s\n", entry->d_name);
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}
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closedir(dir);
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}
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free(dirname);
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if ( 0 <= child_pid )
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{
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fflush(stdout);
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close(1);
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int exit_status;
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waitpid(child_pid, &exit_status, 0);
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if ( WIFSIGNALED(exit_status) )
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exit(128 + WTERMSIG(exit_status));
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if ( WIFEXITED(exit_status) && WEXITSTATUS(exit_status) )
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exit(WEXITSTATUS(exit_status));
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}
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return 0;
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}
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