Rewrite echo(1).
This commit is contained in:
Jonas 'Sortie' Termansen
parent
caa1b7455c
commit
0708482d9b
186
utils/echo.cpp
186
utils/echo.cpp
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@ -1,6 +1,6 @@
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/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2011.
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Copyright(C) Jonas 'Sortie' Termansen 2011, 2013.
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This program is free software: you can redistribute it and/or modify it
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under the terms of the GNU General Public License as published by the Free
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@ -16,37 +16,197 @@
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this program. If not, see <http://www.gnu.org/licenses/>.
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echo.cpp
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Display a line of text.
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Write arguments to standard output.
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*******************************************************************************/
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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 <errno.h>
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#include <unistd.h>
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#if !defined(VERSIONSTR)
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#define VERSIONSTR "unknown version"
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#endif
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static void help(FILE* fp, const char* argv0)
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{
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fprintf(fp, "Usage: %s [SHORT-OPTION]... [STRING]...\n", argv0);
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fprintf(fp, " or: %s [LONG-OPTION]\n", argv0);
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fprintf(fp, "Echo the STRING(s) to standard output.\n");
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fprintf(fp, "\n");
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fprintf(fp, " -n do not output the trailing newline\n");
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fprintf(fp, " -e enable interpretation of backslash escapes\n");
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fprintf(fp, " -E disable interpretation of backslash escapes (default)\n");
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fprintf(fp, " --help display this help and exit\n");
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fprintf(fp, " --version output version information and exit\n");
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fprintf(fp, "\n");
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fprintf(fp, "If -e is in effect, the following sequences are recognized:\n");
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fprintf(fp, "\n");
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fprintf(fp, " \\\\ backslash\n");
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fprintf(fp, " \\a alert (BEL)\n");
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fprintf(fp, " \\b backspace\n");
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fprintf(fp, " \\c produce no further output\n");
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fprintf(fp, " \\e escape\n");
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fprintf(fp, " \\f form feed\n");
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fprintf(fp, " \\n new line\n");
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fprintf(fp, " \\r carriage return\n");
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fprintf(fp, " \\t horizontal tab\n");
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fprintf(fp, " \\v vertical tab\n");
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fprintf(fp, " \\0NNN byte with octal value NNN (1 to 3 digits)\n");
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fprintf(fp, " \\xHH byte with hexadecimal value HH (1 to 2 digits)\n");
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fprintf(fp, "\n");
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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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fprintf(fp, "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n");
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fprintf(fp, "This is free software: you are free to change and redistribute it.\n");
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fprintf(fp, "There is NO WARRANTY, to the extent permitted by law.\n");
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}
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static bool is_allowed_short_argument(const char* argument)
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{
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if ( argument[0] != '-' )
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return false;
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if ( !argument[1] )
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return false;
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for ( size_t i = 1; argument[i]; i++ )
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{
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switch ( argument[i] )
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{
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case 'e': break;
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case 'E': break;
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case 'n': break;
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default: return false;
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}
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}
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return true;
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}
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int main(int argc, char* argv[])
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{
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int startfrom = 1;
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bool trailingnewline = true;
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if ( 1 < argc && strcmp(argv[1], "-n") == 0 )
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bool newline = true;
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bool escape_sequences = false;
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if ( 2 == argc && !strcmp(argv[1], "--help") )
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help(stdout, argv[0]), exit(0);
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if ( 2 == argc && !strcmp(argv[1], "--version") )
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version(stdout, argv[0]), exit(0);
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for ( int i = 1; i < argc; i++ )
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{
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trailingnewline = false;
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startfrom = 2;
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const char* arg = argv[i];
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if ( !is_allowed_short_argument(arg) )
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break;
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argv[i] = NULL;
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for ( size_t n = 1; arg[n]; n++ )
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{
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switch ( arg[n] )
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{
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case 'e': escape_sequences = true; break;
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case 'E': escape_sequences = false; break;
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case 'n': newline = false; break;
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default: break;
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}
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}
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}
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const char* prefix = "";
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for ( int i = startfrom; i < argc; i++ )
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for ( int i = 1; i < argc; i++ )
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{
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if ( printf("%s%s", prefix, argv[i]) < 0 )
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const char* arg = argv[i];
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if ( !arg )
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continue;
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if ( !escape_sequences )
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{
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perror("<stdout>");
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exit(1);
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if ( printf("%s%s", prefix, arg) < 0 )
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error(1, errno, "<stdout>");
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}
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else
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{
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if ( printf("%s", prefix) < 0 )
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error(1, errno, "<stdout>");
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bool escaped = false;
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for ( size_t i = 0; arg[i]; i++ )
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{
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char c = arg[i];
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if ( escaped && (escaped = false, true) )
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{
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if ( c == '0' && (i++, true) )
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{
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int value = 0;
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if ( '0' <= arg[i] && arg[i] <= '7' )
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value = value * 8 + arg[i] - '0', i++;
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if ( '0' <= arg[i] && arg[i] <= '7' )
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value = value * 8 + arg[i] - '0', i++;
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if ( '0' <= arg[i] && arg[i] <= '7' )
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value = value * 8 + arg[i] - '0', i++;
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if ( 255 < value )
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value &= 255;
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if ( putchar(value) == EOF )
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error(1, errno, "<stdout>");
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i--;
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continue;
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}
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if ( c == 'x' && (i++, true) )
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{
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int value = 0;
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if ( '0' <= arg[i] && arg[i] <= '7' )
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value = value * 16 + arg[i] - '0', i++;
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else if ( 'a' <= arg[i] && arg[i] <= 'f' )
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value = value * 16 + arg[i] - 'a' + 10, i++;
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else if ( 'A' <= arg[i] && arg[i] <= 'F' )
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value = value * 16 + arg[i] - 'A' + 10, i++;
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if ( '0' <= arg[i] && arg[i] <= '7' )
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value = value * 16 + arg[i] - '0', i++;
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else if ( 'a' <= arg[i] && arg[i] <= 'f' )
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value = value * 16 + arg[i] - 'a' + 10, i++;
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else if ( 'A' <= arg[i] && arg[i] <= 'F' )
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value = value * 16 + arg[i] - 'A' + 10, i++;
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if ( putchar(value) == EOF )
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error(1, errno, "<stdout>");
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i--;
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continue;
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}
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switch ( c )
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{
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case '\\': c = '\\'; break;
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case 'a': c = '\a'; break;
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case 'b': c = '\b'; break;
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case 'c': goto no_futher_output;
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case 'e': c = '\e'; break;
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case 'f': c = '\f'; break;
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case 'n': c = '\n'; break;
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case 'r': c = '\r'; break;
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case 't': c = '\t'; break;
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case 'v': c = '\v'; break;
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default: break;
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}
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}
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else if ( c == '\\' )
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{
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escaped = true;
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continue;
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}
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if ( putchar((unsigned char) c) == EOF )
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error(1, errno, "<stdout>");
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}
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if ( escaped && putchar('\\') == EOF )
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error(1, errno, "<stdout>");
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}
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prefix = " ";
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}
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if ( trailingnewline ) { printf("\n"); }
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if ( newline && printf("\n") < 0 )
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error(1, errno, "<stdout>");
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no_futher_output:
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if ( fflush(stdout) != 0 || fsync(1) != 0 )
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error(1, errno, "<stdout>");
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return 0;
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}
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