getpath.c

python s60 1.4.5版本的源代码

/* Portions Copyright (c) 2005 Nokia Corporation */
/* Return the initial module search path. */

#include "Python.h"
#include "osdefs.h"

#ifndef SYMBIAN
#include <sys/types.h>
#include <string.h>

#ifdef WITH_NEXT_FRAMEWORK
#include <mach-o/dyld.h>
#endif

/* Search in some common locations for the associated Python libraries.
 *
 * Two directories must be found, the platform independent directory
 * (prefix), containing the common .py and .pyc files, and the platform
 * dependent directory (exec_prefix), containing the shared library
 * modules.  Note that prefix and exec_prefix can be the same directory,
 * but for some installations, they are different.
 *
 * Py_GetPath() carries out separate searches for prefix and exec_prefix.
 * Each search tries a number of different locations until a ``landmark''
 * file or directory is found.  If no prefix or exec_prefix is found, a
 * warning message is issued and the preprocessor defined PREFIX and
 * EXEC_PREFIX are used (even though they will not work); python carries on
 * as best as is possible, but most imports will fail.
 *
 * Before any searches are done, the location of the executable is
 * determined.  If argv[0] has one or more slashs in it, it is used
 * unchanged.  Otherwise, it must have been invoked from the shell's path,
 * so we search $PATH for the named executable and use that.  If the
 * executable was not found on $PATH (or there was no $PATH environment
 * variable), the original argv[0] string is used.
 *
 * Next, the executable location is examined to see if it is a symbolic
 * link.  If so, the link is chased (correctly interpreting a relative
 * pathname if one is found) and the directory of the link target is used.
 *
 * Finally, argv0_path is set to the directory containing the executable
 * (i.e. the last component is stripped).
 *
 * With argv0_path in hand, we perform a number of steps.  The same steps
 * are performed for prefix and for exec_prefix, but with a different
 * landmark.
 *
 * Step 1. Are we running python out of the build directory?  This is
 * checked by looking for a different kind of landmark relative to
 * argv0_path.  For prefix, the landmark's path is derived from the VPATH
 * preprocessor variable (taking into account that its value is almost, but
 * not quite, what we need).  For exec_prefix, the landmark is
 * Modules/Setup.  If the landmark is found, we're done.
 *
 * For the remaining steps, the prefix landmark will always be
 * lib/python$VERSION/os.py and the exec_prefix will always be
 * lib/python$VERSION/lib-dynload, where $VERSION is Python's version
 * number as supplied by the Makefile.  Note that this means that no more
 * build directory checking is performed; if the first step did not find
 * the landmarks, the assumption is that python is running from an
 * installed setup.
 *
 * Step 2. See if the $PYTHONHOME environment variable points to the
 * installed location of the Python libraries.  If $PYTHONHOME is set, then
 * it points to prefix and exec_prefix.  $PYTHONHOME can be a single
 * directory, which is used for both, or the prefix and exec_prefix
 * directories separated by a colon.
 *
 * Step 3. Try to find prefix and exec_prefix relative to argv0_path,
 * backtracking up the path until it is exhausted.  This is the most common
 * step to succeed.  Note that if prefix and exec_prefix are different,
 * exec_prefix is more likely to be found; however if exec_prefix is a
 * subdirectory of prefix, both will be found.
 *
 * Step 4. Search the directories pointed to by the preprocessor variables
 * PREFIX and EXEC_PREFIX.  These are supplied by the Makefile but can be
 * passed in as options to the configure script.
 *
 * That's it!
 *
 * Well, almost.  Once we have determined prefix and exec_prefix, the
 * preprocessor variable PYTHONPATH is used to construct a path.  Each
 * relative path on PYTHONPATH is prefixed with prefix.  Then the directory
 * containing the shared library modules is appended.  The environment
 * variable $PYTHONPATH is inserted in front of it all.  Finally, the
 * prefix and exec_prefix globals are tweaked so they reflect the values
 * expected by other code, by stripping the "lib/python$VERSION/..." stuff
 * off.  If either points to the build directory, the globals are reset to
 * the corresponding preprocessor variables (so sys.prefix will reflect the
 * installation location, even though sys.path points into the build
 * directory).  This seems to make more sense given that currently the only
 * known use of sys.prefix and sys.exec_prefix is for the ILU installation
 * process to find the installed Python tree.
 */

#ifndef VERSION
#define VERSION "2.1"
#endif

#ifndef VPATH
#define VPATH "."
#endif

#ifndef PREFIX
#define PREFIX "/usr/local"
#endif

#ifndef EXEC_PREFIX
#define EXEC_PREFIX PREFIX
#endif

#ifndef PYTHONPATH
#define PYTHONPATH PREFIX "/lib/python" VERSION ":" \
              EXEC_PREFIX "/lib/python" VERSION "/lib-dynload"
#endif

#ifndef LANDMARK
#define LANDMARK "os.py"
#endif

static char prefix[MAXPATHLEN+1];
static char exec_prefix[MAXPATHLEN+1];
static char progpath[MAXPATHLEN+1];
static char *module_search_path = NULL;
static char lib_python[] = "lib/python" VERSION;

static void
reduce(char *dir)
{
    size_t i = strlen(dir);
    while (i > 0 && dir[i] != SEP)
        --i;
    dir[i] = '\0';
}


static int
isfile(char *filename)          /* Is file, not directory */
{
    struct stat buf;
    if (stat(filename, &buf) != 0)
        return 0;
    if (!S_ISREG(buf.st_mode))
        return 0;
    return 1;
}


static int
ismodule(char *filename)        /* Is module -- check for .pyc/.pyo too */
{
    if (isfile(filename))
        return 1;

    /* Check for the compiled version of prefix. */
    if (strlen(filename) < MAXPATHLEN) {
        strcat(filename, Py_OptimizeFlag ? "o" : "c");
        if (isfile(filename))
            return 1;
    }
    return 0;
}


static int
isxfile(char *filename)         /* Is executable file */
{
    struct stat buf;
    if (stat(filename, &buf) != 0)
        return 0;
    if (!S_ISREG(buf.st_mode))
        return 0;
    if ((buf.st_mode & 0111) == 0)
        return 0;
    return 1;
}


static int
isdir(char *filename)                   /* Is directory */
{
    struct stat buf;
    if (stat(filename, &buf) != 0)
        return 0;
    if (!S_ISDIR(buf.st_mode))
        return 0;
    return 1;
}


/* joinpath requires that any buffer argument passed to it has at
   least MAXPATHLEN + 1 bytes allocated.  If this requirement is met,
   it guarantees that it will never overflow the buffer.  If stuff
   is too long, buffer will contain a truncated copy of stuff.
*/
static void
joinpath(char *buffer, char *stuff)
{
    size_t n, k;
    if (stuff[0] == SEP)
        n = 0;
    else {
        n = strlen(buffer);
        if (n > 0 && buffer[n-1] != SEP && n < MAXPATHLEN)
            buffer[n++] = SEP;
    }
    k = strlen(stuff);
    if (n + k > MAXPATHLEN)
        k = MAXPATHLEN - n;
    strncpy(buffer+n, stuff, k);
    buffer[n+k] = '\0';
}

/* copy_absolute requires that path be allocated at least
   MAXPATHLEN + 1 bytes and that p be no more than MAXPATHLEN bytes. */
static void
copy_absolute(char *path, char *p)
{
    if (p[0] == SEP)
        strcpy(path, p);
    else {
        getcwd(path, MAXPATHLEN);
        if (p[0] == '.' && p[1] == SEP)
            p += 2;
        joinpath(path, p);
    }
}

/* absolutize() requires that path be allocated at least MAXPATHLEN+1 bytes. */
static void
absolutize(char *path)
{
    char buffer[MAXPATHLEN + 1];

    if (path[0] == SEP)
        return;
    copy_absolute(buffer, path);
    strcpy(path, buffer);
}

/* search_for_prefix requires that argv0_path be no more than MAXPATHLEN
   bytes long.
*/
static int
search_for_prefix(char *argv0_path, char *home)
{
    size_t n;
    char *vpath;

    /* If PYTHONHOME is set, we believe it unconditionally */
    if (home) {
        char *delim;
        strncpy(prefix, home, MAXPATHLEN);
        delim = strchr(prefix, DELIM);
        if (delim)
            *delim = '\0';
        joinpath(prefix, lib_python);
        joinpath(prefix, LANDMARK);
        return 1;
    }

    /* Check to see if argv[0] is in the build directory */
    strcpy(prefix, argv0_path);
    joinpath(prefix, "Modules/Setup");
    if (isfile(prefix)) {
        /* Check VPATH to see if argv0_path is in the build directory. */
        vpath = VPATH;
        strcpy(prefix, argv0_path);
        joinpath(prefix, vpath);
        joinpath(prefix, "Lib");
        joinpath(prefix, LANDMARK);
        if (ismodule(prefix))
            return -1;
    }

    /* Search from argv0_path, until root is found */
    copy_absolute(prefix, argv0_path);
    do {
        n = strlen(prefix);
        joinpath(prefix, lib_python);
        joinpath(prefix, LANDMARK);
        if (ismodule(prefix))
            return 1;
        prefix[n] = '\0';
        reduce(prefix);
    } while (prefix[0]);

    /* Look at configure's PREFIX */
    strncpy(prefix, PREFIX, MAXPATHLEN);
    joinpath(prefix, lib_python);
    joinpath(prefix, LANDMARK);
    if (ismodule(prefix))
        return 1;

    /* Fail */
    return 0;
}


/* search_for_exec_prefix requires that argv0_path be no more than
   MAXPATHLEN bytes long.
*/
static int
search_for_exec_prefix(char *argv0_path, char *home)
{
    size_t n;

    /* If PYTHONHOME is set, we believe it unconditionally */
    if (home) {
        char *delim;
        delim = strchr(home, DELIM);
        if (delim)
            strncpy(exec_prefix, delim+1, MAXPATHLEN);
        else
            strncpy(exec_prefix, home, MAXPATHLEN);
        joinpath(exec_prefix, lib_python);
        joinpath(exec_prefix, "lib-dynload");
        return 1;
    }

    /* Check to see if argv[0] is in the build directory */
    strcpy(exec_prefix, argv0_path);
    joinpath(exec_prefix, "Modules/Setup");
    if (isfile(exec_prefix)) {
        reduce(exec_prefix);
        return -1;
    }

    /* Search from argv0_path, until root is found */
    copy_absolute(exec_prefix, argv0_path);
    do {
        n = strlen(exec_prefix);
        joinpath(exec_prefix, lib_python);