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sortix--sortix/utils/which.cpp
2015-12-12 19:28:07 +01:00

200 lines
4.4 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012, 2014.
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/>.
which.cpp
Locate a program in the PATH.
*******************************************************************************/
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <error.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
// NOTE: The PATH-searching logic is repeated multiple places. Until this logic
// can be shared somehow, you need to keep this comment in sync as well
// as the logic in these files:
// * kernel/process.cpp
// * libc/unistd/execvpe.cpp
// * utils/which.cpp
// NOTE: See comments in execvpe() for algorithmic commentary.
bool Which(const char* filename, const char* path, bool all)
{
bool found = false;
bool search_path = !strchr(filename, '/') && path;
bool any_tries = false;
bool any_eacces = false;
while ( search_path && *path )
{
size_t len = strcspn(path, ":");
if ( !len )
{
path++;
continue;
}
any_tries = true;
char* dirpath = strndup(path, len);
if ( !dirpath )
return -1;
if ( (path += len)[0] == ':' )
path++;
while ( len && dirpath[len - 1] == '/' )
dirpath[--len] = '\0';
char* fullpath;
if ( asprintf(&fullpath, "%s/%s", dirpath, filename) < 0 )
return free(dirpath), -1;
if ( access(fullpath, X_OK) == 0 )
{
found = true;
printf("%s\n", fullpath);
free(fullpath);
free(dirpath);
if ( all )
continue;
break;
}
free(fullpath);
free(dirpath);
if ( errno == ENOENT )
continue;
if ( errno == ELOOP ||
errno == EISDIR ||
errno == ENAMETOOLONG ||
errno == ENOTDIR )
continue;
if ( errno == EACCES )
{
any_eacces = true;
continue;
}
if ( all )
continue;
break;
}
if ( !any_tries )
{
if ( access(filename, X_OK) == 0 )
{
found = true;
printf("%s\n", filename);
}
}
(void) any_eacces;
return found;
}
static void compact_arguments(int* argc, char*** argv)
{
for ( int i = 0; i < *argc; i++ )
{
while ( i < *argc && !(*argv)[i] )
{
for ( int n = i; n < *argc; n++ )
(*argv)[n] = (*argv)[n+1];
(*argc)--;
}
}
}
static void help(FILE* fp, const char* argv0)
{
fprintf(fp, "Usage: %s [-a] FILENAME...\n", argv0);
fprintf(fp, "Locate a program in the PATH.\n");
}
static void version(FILE* fp, const char* argv0)
{
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];
bool all = false;
for ( int i = 1; i < argc; i++ )
{
const char* arg = argv[i];
if ( arg[0] != '-' || !arg[1] )
continue;
argv[i] = NULL;
if ( !strcmp(arg, "--") )
break;
if ( arg[1] != '-' )
{
while ( char c = *++arg ) switch ( c )
{
case 'a': all = true; break;
default:
fprintf(stderr, "%s: unknown option -- '%c'\n", argv0, arg[i]);
help(stderr, argv0);
exit(1);
}
}
else if ( !strcmp(arg, "--help") )
help(stdout, argv0), exit(0);
else if ( !strcmp(arg, "--version") )
version(stdout, argv0), exit(0);
else
{
fprintf(stderr, "%s: unknown option: %s\n", argv0, arg);
help(stderr, argv0);
exit(1);
}
}
compact_arguments(&argc, &argv);
if ( argc < 2 )
error(1, 0, "missing operand");
const char* path = getenv("PATH");
bool success = true;
for ( int i = 1; i < argc; i++ )
{
const char* arg = argv[i];
if ( !Which(arg, path, all) )
success = false;
}
return success ? 0 : 1;
}