library/unistd_execvp.c
/*
* $Id: unistd_execvp.c,v 1.7 2006-09-25 14:51:15 obarthel Exp $
*
* :ts=4
*
* Portable ISO 'C' (1994) runtime library for the Amiga computer
* Copyright (c) 2002-2015 by Olaf Barthel <obarthel (at) gmx.net>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Neither the name of Olaf Barthel nor the names of contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _UNISTD_HEADERS_H
#include "unistd_headers.h"
#endif /* _UNISTD_HEADERS_H */
/****************************************************************************/
/* The following is not part of the ISO 'C' (1994) standard. */
/****************************************************************************/
/* A local version of the BSD strsep() function. */
static char *
local_strsep(char ** string_ptr, const char * delimiter)
{
char * result = NULL;
char * string;
assert( string_ptr != NULL && delimiter != NULL );
string = (*string_ptr);
if(string != NULL)
{
char * token = string;
char c;
while(TRUE)
{
c = (*string++);
/* Reached the end of the string? */
if(c == '\0')
{
/* No further string data available. */
(*string_ptr) = NULL;
result = token;
break;
}
/* Is that character a delimiter? */
if(strchr(delimiter,c) != NULL)
{
/* NUL-terminate the string, overwriting
the delimiter character */
string[-1] = '\0';
/* Scanning can resume with the next following
character. */
(*string_ptr) = string;
result = token;
break;
}
}
}
return(result);
}
/****************************************************************************/
int
execvp(const char *command,char * const argv[])
{
char * command_buffer = NULL;
size_t command_name_len,i;
char * path_copy = NULL;
int result = -1;
BOOL found_path_separators;
/* Do not allow null command */
if(command == NULL || (*command) == '\0')
{
__set_errno(ENOENT);
goto out;
}
command_name_len = strlen(command);
/* Check if there are any path separator characters in the
command name. */
found_path_separators = FALSE;
for(i = 0 ; i < command_name_len ; i++)
{
if(command[i] == '/' || command[i] == ':')
{
found_path_separators = TRUE;
break;
}
}
/* If it's an absolute or relative path name, it's easy. */
if(found_path_separators)
{
result = execve(command, argv, environ);
}
else
{
size_t command_buffer_size = 0;
const char * path_delimiter;
char * path;
const char * search_prefix;
size_t search_prefix_len;
size_t complete_path_len;
int error;
/* We first look up the PATH environment variable because
we will be making a copy of it. This avoids trouble
lateron when we will be calling getenv() again. */
path = getenv("PATH");
if(path == NULL)
path = (char *)__default_path;
path_copy = strdup(path);
if(path_copy == NULL)
{
__set_errno(ENOMEM);
goto out;
}
path = path_copy;
path_delimiter = getenv("PATH_SEPARATOR");
if(path_delimiter == NULL)
path_delimiter = __default_path_delimiter;
while((search_prefix = local_strsep(&path,path_delimiter)) != NULL)
{
if((*search_prefix) == '\0')
search_prefix = ".";
search_prefix_len = strlen(search_prefix);
complete_path_len = search_prefix_len + 1 + command_name_len;
if(complete_path_len + 1 > command_buffer_size)
{
char * new_command_buffer;
/* Allocate a little more memory than we
really need. */
new_command_buffer = malloc(complete_path_len + 10);
if(new_command_buffer == NULL)
{
__set_errno(ENOMEM);
goto out;
}
if(command_buffer != NULL)
free(command_buffer);
command_buffer = new_command_buffer;
command_buffer_size = complete_path_len + 10;
}
/* Combine the search prefix with the command name. */
memcpy(command_buffer,search_prefix,search_prefix_len);
command_buffer[search_prefix_len] = '/';
memcpy(&command_buffer[search_prefix_len+1],command,command_name_len);
command_buffer[complete_path_len] = '\0';
/* Now try to run that command. */
result = execve(command_buffer, argv, environ);
/* Did it work? And if it didn't work, did it fail because
the command to be run could not be executed? */
error = __get_errno();
if(result == 0 ||
(error != EACCES &&
error != EISDIR &&
error != ENOENT &&
error != ENOEXEC &&
error != EPERM))
{
break;
}
/* Just in case somebody wants to quit... */
__check_abort();
}
}
out:
if(path_copy != NULL)
free(path_copy);
if(command_buffer != NULL)
free(command_buffer);
return(result);
}