104 lines
2.6 KiB
C
104 lines
2.6 KiB
C
#include <errno.h> /* errno */
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#include <stdio.h> /* fprintf(3), getc(3), putc(3), stderr, stdin, stdout, EOF,
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* NULL */
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#include <stdlib.h> /* size_t */
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#include <string.h> /* strerror(3) */
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#if !defined EX_OK || !defined EX_OSERR || !defined EX_USAGE
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# include <sysexits.h>
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#endif
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#include <termios.h> /* tcgetattr(3), tcsetattr(3), struct termios, ECHO */
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#include <unistd.h> /* dup(2), execvp(3), fork(2), getopt(3), isatty(3),
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* pipe(2), STDIN_FILENO */
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static char *program_name = "peek";
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int main(int argc, char *argv[]){
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int c;
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int eof;
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size_t i;
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char include_eof;
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FILE *outputs[] = {
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NULL /* stdout */,
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NULL /* stderr */,
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NULL /* -p */
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};
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int p[2] = {0, 0};
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struct termios t;
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if(argc < 1)
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goto usage;
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eof = EOF;
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include_eof = 0;
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while((c = getopt(argc, argv, "1enopt")) != -1)
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switch(c){
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case '1': eof = '\n'; break;
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case 'n': include_eof = 1; break;
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case 'o': outputs[0] = stdout; break;
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case 'e': outputs[1] = stderr; break;
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case 'p':
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if(pipe(p) != 0)
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goto die;
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else if((outputs[2] = fdopen(p[1], "ab")) == NULL)
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goto die;
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break;
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case 't':
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if(isatty(STDIN_FILENO) != 1){
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fprintf(stderr, "%s: Must be run in a terminal"
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" (option -t specified)\n", argv[0]);
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return EX_USAGE;
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}
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default: goto usage;
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}
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/* If -p is used there must be additional arguments. Getopt(3) wouldn't
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* work for this because optarg would have to be one string to give to
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* system(3) or an equivalent and it would be a mess of parsing and
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* security issues. Any intended usage works with this slightly funkier
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* argument parsing, unintended usages work as happy coincidence. */
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if((argc > optind) == (outputs[2] == 0)){
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usage: fprintf(stderr, "Usage: %s (-1enot)"
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" (-p [program [arguments...]])\n",
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argv[0] == NULL ? program_name : argv[0]);
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return EX_USAGE;
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}
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if(outputs[2] != 0)
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switch(fork()){
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case 0:
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if(close(p[1]) == 0
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&& dup2(p[0], STDIN_FILENO)
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== STDIN_FILENO)
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execvp(argv[optind], argv + optind);
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case -1:
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goto die;
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default:
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if(close(p[0]) != 0)
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goto die;
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}
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/* terminal echo */
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tcgetattr(STDIN_FILENO, &t);
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t.c_lflag ^= ECHO;
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tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
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do{ if((c = getc(stdin)) != eof || include_eof)
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for(i = 0; i < (sizeof outputs)/(sizeof *outputs); ++i)
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if(outputs[i] != NULL
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&& putc(c, outputs[i]) == EOF){
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if(i == 2)
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fclose(outputs[i]);
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outputs[i] = 0;
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}
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}while(c != eof);
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tcgetattr(STDIN_FILENO, &t);
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t.c_lflag |= ECHO;
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tcsetattr(STDIN_FILENO, TCSAFLUSH, &t);
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return EX_OK;
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die: fprintf(stderr, "%s: %s\n", argv[0], strerror(errno));
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return EX_OSERR;
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}
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