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sortix--sortix/utils/cat.cpp

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/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
This program is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
more details.
You should have received a copy of the GNU General Public License along with
this program. If not, see <http://www.gnu.org/licenses/>.
cat.cpp
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Concatenate and print files to the standard output.
*******************************************************************************/
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#include <sys/stat.h>
#include <errno.h>
#include <error.h>
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#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#if !defined(VERSIONSTR)
#define VERSIONSTR "unknown version"
#endif
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static bool cat_fd(int fd, const char* path)
{
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struct stat st;
if ( fstat(fd, &st) == 0 )
{
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if ( S_ISDIR(st.st_mode) )
return error(0, EISDIR, "`%s'", path), false;
}
const size_t BUFFER_SIZE = 16 * 1024;
uint8_t buffer[BUFFER_SIZE];
ssize_t buffer_used;
while ( 0 < (buffer_used = read(fd, buffer, BUFFER_SIZE)) )
{
size_t so_far = 0;
while ( so_far < (size_t) buffer_used )
{
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ssize_t amount = write(1, buffer + so_far, buffer_used - so_far);
if ( amount <= 0 )
return error(0, errno, "`%s'", "<stdout>"), false;
so_far += amount;
}
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}
if ( buffer_used < 0 )
return error(0, errno, "`%s'", path), false;
return true;
}
static bool cat_path(const char* path)
{
if ( !strcmp("-", path) )
return cat_fd(0, "<stdin>");
int fd = open(path, O_RDONLY);
if ( fd < 0 )
{
error(0, errno, "`%s'", path);
return false;
}
bool result = cat_fd(fd, path);
close(fd);
return result;
}
static bool cat_arguments(int argc, char* argv[])
{
if ( argc <= 1 )
return cat_path("-");
bool success = true;
for ( int i = 1; i < argc; i++ )
if ( !cat_path(argv[i]) )
success = false;
return success;
}
static void compact_arguments(int* argc, char*** argv)
{
for ( int i = 0; i < *argc; i++ )
while ( i < *argc && !(*argv)[i] )
{
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for ( int n = i; n < *argc; n++ )
(*argv)[n] = (*argv)[n+1];
(*argc)--;
}
}
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static void usage(FILE* fp, const char* argv0)
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{
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fprintf(fp, "Usage: %s [OPTION]... [FILE]...\n", argv0);
fprintf(fp, "Concatenate FILE(s), or standard input, to standard output.\n");
fprintf(fp, "\n");
fprintf(fp, " -u (ignored)\n");
fprintf(fp, " --help display this help and exit\n");
fprintf(fp, " --usage display this help and exit\n");
fprintf(fp, " --version output version information and exit\n");
fprintf(fp, "\n");
fprintf(fp, "With no FILE, or when FILE is -, read standard input.\n");
}
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static void help(FILE* fp, const char* argv0)
{
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usage(fp, argv0);
}
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static void version(FILE* fp, const char* argv0)
{
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fprintf(fp, "%s (Sortix) %s\n", argv0, VERSIONSTR);
fprintf(fp, "License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.\n");
fprintf(fp, "This is free software: you are free to change and redistribute it.\n");
fprintf(fp, "There is NO WARRANTY, to the extent permitted by law.\n");
}
int main(int argc, char* argv[])
{
const char* argv0 = argv[0];
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for ( int i = 1; i < argc; i++ )
{
const char* arg = argv[i];
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if ( arg[0] != '-' || !arg[1] )
continue;
argv[i] = NULL;
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if ( !strcmp(arg, "--") )
break;
if ( arg[1] != '-' )
{
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while ( char c = *++arg ) switch ( c )
{
case 'u': /* Ignored, POSIX compatibility. */ break;
default:
fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, c);
usage(stderr, argv0);
exit(1);
}
}
else if ( !strcmp(arg, "--help") )
help(stdout, argv0), exit(0);
else if ( !strcmp(arg, "--usage") )
usage(stdout, argv0), exit(0);
else if ( !strcmp(arg, "--version") )
version(stdout, argv0), exit(0);
else
{
fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
usage(stderr, argv0);
exit(1);
}
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}
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compact_arguments(&argc, &argv);
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return cat_arguments(argc, argv) ? 0 : 1;
}