mirror of
https://gitlab.com/sortix/sortix.git
synced 2023-02-13 20:55:38 -05:00
240 lines
5.4 KiB
C
240 lines
5.4 KiB
C
/*
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* Copyright (c) 2012, 2015 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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* tail.c
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* Output the last part of files.
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*/
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#include <sys/stat.h>
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#include <ctype.h>
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#include <errno.h>
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#include <error.h>
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#include <stdbool.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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#ifdef HEAD
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#define TAIL false
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#else
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#define TAIL true
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#endif
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const char* STDINNAME = "standard input";
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long numlines = 10;
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bool quiet = false;
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bool verbose = false;
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bool processfp(const char* inputname, FILE* fp)
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{
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struct stat st;
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if ( fstat(fileno(fp), &st) == 0 && S_ISDIR(st.st_mode) )
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{
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error(0, EISDIR, "%s", inputname);
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return false;
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}
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const bool tail = TAIL;
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const bool head = !TAIL;
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if ( !numlines ) { return true; }
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bool specialleading = (head && 0 < numlines) || (tail && numlines < 0);
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bool specialtrailing = !specialleading;
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long abslines = (numlines < 0) ? -numlines : numlines;
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char** buffer = NULL;
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if ( specialtrailing )
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buffer = (char**) calloc(1, sizeof(char*) * abslines);
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long linenum;
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for ( linenum = 0; true; linenum++ )
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{
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char* line = NULL;
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size_t linesize;
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ssize_t linelen = getline(&line, &linesize, fp);
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if ( linelen < 0 )
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{
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if ( ferror(fp) )
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error(1, errno, "%s", inputname);
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free(line);
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break;
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}
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if ( specialleading )
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{
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bool doprint = false;
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if ( head && linenum < abslines ) { doprint = true; }
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else if ( tail && abslines <= linenum ) { doprint = true; }
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bool done = head && abslines <= linenum+1;
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if ( doprint ) { printf("%s", line); }
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free(line);
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if ( done ) { return true; }
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}
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if ( specialtrailing )
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{
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long index = linenum % abslines;
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if ( buffer[index] )
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{
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char* bufline = buffer[index];
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if ( head ) { printf("%s", bufline); }
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free(bufline);
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}
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buffer[index] = line;
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}
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}
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if ( specialtrailing && tail )
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{
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long numtoprint = linenum < abslines ? linenum : abslines;
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for ( long i = 0; i < numtoprint; i++ )
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{
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long index = (linenum - numtoprint + i) % abslines;
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printf("%s", buffer[index]);
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free(buffer[index]);
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}
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}
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free(buffer);
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return true;
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}
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static void compact_arguments(int* argc, char*** argv)
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{
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for ( int i = 0; i < *argc; i++ )
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{
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while ( i < *argc && !(*argv)[i] )
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{
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for ( int n = i; n < *argc; n++ )
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(*argv)[n] = (*argv)[n+1];
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(*argc)--;
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}
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}
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}
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static void help(FILE* fp, const char* argv0)
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{
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fprintf(fp, "Usage: %s [OPTION]... [FILE]...\n", argv0);
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}
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static void version(FILE* fp, const char* argv0)
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{
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fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
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}
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int main(int argc, char* argv[])
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{
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const char* nlinesstr = NULL;
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const char* argv0 = argv[0];
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for ( int i = 1; i < argc; i++ )
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{
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const char* arg = argv[i];
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if ( arg[0] != '-' || !arg[1] )
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continue;
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argv[i] = NULL;
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if ( !strcmp(arg, "--") )
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break;
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if ( isdigit((unsigned char) arg[1]) )
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nlinesstr = arg + 1;
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else if ( arg[1] != '-' )
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{
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char c;
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while ( (c = *++arg) ) switch ( c )
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{
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case 'n':
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if ( !*(nlinesstr = arg + 1) )
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{
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if ( i + 1 == argc )
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{
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error(0, 0, "option requires an argument -- 'n'");
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fprintf(stderr, "Try `%s --help' for more information.\n", argv[0]);
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exit(125);
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}
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nlinesstr = argv[i+1];
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argv[++i] = NULL;
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}
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arg = "n";
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break;
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case 'q': quiet = true; verbose = false; break;
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case 'v': quiet = false; verbose = true; break;
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default:
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fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, c);
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help(stderr, argv0);
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exit(1);
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}
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}
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else if ( !strcmp(arg, "--help") )
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help(stdout, argv0), exit(0);
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else if ( !strcmp(arg, "--version") )
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version(stdout, argv0), exit(0);
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else if ( !strcmp(arg, "--quiet") || !strcmp(arg, "--silent") )
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quiet = true, verbose = false;
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else if ( !strcmp(arg, "--verbose") )
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quiet = false, verbose = true;
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else
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{
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fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
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help(stderr, argv0);
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exit(1);
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}
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}
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compact_arguments(&argc, &argv);
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if ( nlinesstr )
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{
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char* nlinesstrend;
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long nlines = strtol(nlinesstr, &nlinesstrend, 10);
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if ( *nlinesstrend )
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error(1, 0, "Bad number of lines: %s", nlinesstr);
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numlines = nlines;
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}
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if ( argc < 2 )
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{
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bool header = verbose;
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if ( header )
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printf("==> %s <==\n", STDINNAME);
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if ( !processfp(STDINNAME, stdin) )
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return 1;
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return 0;
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}
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int result = 0;
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const char* prefix = "";
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for ( int i = 1; i < argc; i++ )
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{
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bool isstdin = strcmp(argv[i], "-") == 0;
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FILE* fp = isstdin ? stdin : fopen(argv[i], "r");
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if ( !fp )
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{
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error(0, errno, "%s", argv[i]);
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result = 1;
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continue;
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}
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bool header = !quiet && (verbose || 2 < argc);
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if ( header )
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printf("%s==> %s <==\n", prefix, argv[i]);
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prefix = "\n";
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if ( !processfp(isstdin ? STDINNAME : argv[i], fp) )
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result = 1;
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if ( !isstdin )
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fclose(fp);
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}
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return result;
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}
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