/****************************************************************************
* binfmt/binfmt_exepath.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <nuttx/kmalloc.h>
#include <nuttx/binfmt/binfmt.h>
#if !defined(CONFIG_BINFMT_DISABLE) && defined(CONFIG_BINFMT_EXEPATH)
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Types
****************************************************************************/
struct exepath_s
{
FAR char *next; /* Pointer to the next (unterminated) value in the PATH variable */
char path[1];
};
#define SIZEOF_EXEPATH_S(n) (sizeof(struct exepath_s) + (n) - 1)
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: exepath_init
*
* Description:
* Initialize for the traversal of each value in the PATH variable. The
* usage is sequence is as follows:
*
* 1) Call exepath_init() to initialize for the traversal. exepath_init()
* will return an opaque handle that can then be provided to
* exepath_next() and exepath_release().
* 2) Call exepath_next() repeatedly to examine every file that lies
* in the directories of the PATH variable
* 3) Call exepath_release() to free resources set aside by exepath_init().
*
* Input Parameters:
* None
*
* Returned Value:
* On success, exepath_init() return a non-NULL, opaque handle that may
* subsequently be used in calls to exepath_next() and exepath_release().
* On error, a NULL handle value will be returned. The most likely cause
* of an error would be that the there is no value associated with the
* PATH variable.
*
****************************************************************************/
EXEPATH_HANDLE exepath_init(void)
{
FAR struct exepath_s *exepath;
FAR char *path;
/* Get the value of the PATH variable */
path = getenv("PATH");
if (!path)
{
/* getenv() will return a NULL value if the PATH variable does not
* exist in the environment.
*/
return (EXEPATH_HANDLE)NULL;
}
/* Allocate a container for the PATH variable contents */
exepath = (FAR struct exepath_s *)kmm_malloc(SIZEOF_EXEPATH_S(strlen(path) + 1));
if (!exepath)
{
/* Ooops.. we are out of memory */
return (EXEPATH_HANDLE)NULL;
}
/* Populate the container */
strcpy(exepath->path, path);
exepath->next = exepath->path;
/* And return the containing cast to an opaque handle */
return (EXEPATH_HANDLE)exepath;
}
/****************************************************************************
* Name: exepath_next
*
* Description:
* Traverse all possible values in the PATH variable in attempt to find
* the full path to an executable file when only a relative path is
* provided.
*
* Input Parameters:
* handle - The handle value returned by exepath_init
* relpath - The relative path to the file to be found.
*
* Returned Value:
* On success, a non-NULL pointer to a null-terminated string is provided.
* This is the full path to a file that exists in the file system. This
* function will verify that the file exists (but will not verify that it
* is marked executable).
*
* NOTE: The string pointer return in the success case points to allocated
* memory. This memory must be freed by the called by calling kmm_free().
*
* NULL is returned if no path is found to any file with the provided
* 'relpath' from any absolute path in the PATH variable. In this case,
* there is no point in calling exepath_next() further; exepath_release()
* must be called to release resources set aside by expath_init().
*
****************************************************************************/
FAR char *exepath_next(EXEPATH_HANDLE handle, FAR const char *relpath)
{
FAR struct exepath_s *exepath = (FAR struct exepath_s *)handle;
struct stat buf;
FAR char *endptr;
FAR char *path;
FAR char *fullpath;
int pathlen;
int ret;
/* Verify that a value handle and relative path were provided */
DEBUGASSERT(exepath && relpath);
DEBUGASSERT(relpath[0] != '\0' && relpath[0] != '/');
/* Loop until (1) we find a file with this relative path from one of the
* absolute paths in the PATH variable, or (2) all of the absolute paths
* in the PATH variable have been considered.
*/
for (;;)
{
/* Make sure that exepath->next points to the beginning of a string */
path = exepath->next;
if (*path == '\0')
{
/* If it points to a NULL it means that either (1) the PATH varialbe
* is empty, or (2) we have already examined all of the paths in the
* path variable.
*/
return (FAR char *)NULL;
}
/* Okay... 'path' points to the beginning of the string. The string may
* be termined either with (1) ':' which separates the path from the
* next path in the list, or (2) NUL which marks the end of the list.
*/
endptr = strchr(path, ':');
if (!endptr)
{
/* If strchr returns NUL it means that ':' does not appear in the
* string. Therefore, this must be the final path in the PATH
* variable content.
*/
endptr = &path[strlen(path)];
exepath->next = endptr;
DEBUGASSERT(*endptr == '\0');
}
else
{
DEBUGASSERT(*endptr == ':');
exepath->next = endptr + 1;
*endptr = '\0';
}
pathlen = strlen(path) + strlen(relpath) + 2;
fullpath = (FAR char *)kmm_malloc(pathlen);
if (!fullpath)
{
/* Failed to allocate memory */
return (FAR char *)NULL;
}
/* Construct the full path */
sprintf(fullpath, "%s/%s", path, relpath);
/* Verify that a regular file exists at this path */
ret = stat(fullpath, &buf);;
if (ret == OK && S_ISREG(buf.st_mode))
{
return fullpath;
}
/* Failed to stat the file. Just free the allocated memory and
* continue to try the next path.
*/
kmm_free(fullpath);
}
/* We will not get here */
}
/****************************************************************************
* Name: exepath_release
*
* Description:
* Release all resources set aside by exepath_init() when the handle value
* was created. The handle value is invalid on return from this function.
* Attempts to all exepath_next() or exepath_release() with such a 'stale'
* handle will result in undefined (i.e., not good) behavior.
*
* Input Parameters:
* handle - The handle value returned by exepath_init
*
* Returned Value:
* None
*
****************************************************************************/
void exepath_release(EXEPATH_HANDLE handle)
{
kmm_free(handle);
}
#endif /* !CONFIG_BINFMT_DISABLE && CONFIG_BINFMT_EXEPATH */
