Completely revamped the way the default path is constructed.
Idea and first three implementation rounds due to Barry -- after that
I spent another day on it, hopefully it's enough for now :-)
(Wait for the checkin to Setup.in.)
diff --git a/Modules/getpath.c b/Modules/getpath.c
index 8b08b6c..8dcf14e 100644
--- a/Modules/getpath.c
+++ b/Modules/getpath.c
@@ -34,9 +34,104 @@
#include "Python.h"
#include "osdefs.h"
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <strings.h>
-#ifndef PYTHONPATH
-#define PYTHONPATH "/usr/local/lib/python"
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif /* HAVE_UNISTD_H */
+
+/* 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 defines 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 a slash in it (or more), this is it;
+ * 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 $PATH
+ * environment variable), the original argv[0] string is used.
+ *
+ * Next, either the executable location is examined to see if it is a
+ * symbolic link. If so, the link is chased (correctly interpreting a
+ * relative pathname if one is found) and the directory of the link
+ * target is used as instead.
+ *
+ * Finally, argv0_path is set to the directory containing the
+ * executable (i.e. the last component is stripped).
+ *
+ * With argv0_path in hand, we perform a number of steps. The same
+ * steps are performed for prefix and for exec_prefix, but with a
+ * different landmark.
+ *
+ * Step 1. Are we running python out of the build directory? This is
+ * checked by looking for a different kind of landmark relative to
+ * argv0_path. For prefix, the landmark's path is derived from the
+ * VPATH preprocessor variable (taking into account that its value is
+ * almost, but not quite, what we need). If the landmark is found,
+ * we're done.
+ *
+ * For the remaining steps, the prefix landmark will always be
+ * lib/python$VERSION/string.py and the exec_prefix will always be
+ * lib/python$VERSION/sharedmodules, 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
+ * two steps 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.
+ *
+ * Step 5. Search some `standard' directories, namely: /usr/local,
+ * /usr, then finally /.
+ *
+ * That's it! Well, almost. Once we have determined prefix and
+ * exec_prefix, the preprocesor 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 $PYTHONPATH is
+ * inserted in front of it all. Finally, the prefix and exec_prefix
+ * globals are tweaked so the reflect the values expected by other
+ * code, by stripping the "lib/python$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 "1.5"
+#endif
+
+#ifndef VPATH
+#define VPATH "."
#endif
#ifndef PREFIX
@@ -47,51 +142,453 @@
#define EXEC_PREFIX PREFIX
#endif
+#ifndef PYTHONPATH
+/* I know this isn't K&R C, but the Makefile specifies it anyway */
+#define PYTHONPATH PREFIX "/lib/python" VERSION ":" \
+ PREFIX "/lib/python" VERSION "/test" ":" \
+ EXEC_PREFIX "/lib/python" VERSION "/sharedmodules"
+#endif
-/* This is called once from pythonrun to initialize sys.path. The
- environment variable PYTHONPATH is fetched and the default path
- appended. The default path may be passed to the preprocessor; if
- not, a hardcoded default is used, which only makes (some) sense on
- Unix. */
+#ifndef LANDMARK
+#define LANDMARK "string.py"
+#endif
+
+static char *std_dirs[] = {"/usr/local/", "/usr/", "/", NULL};
+
+static char prefix[MAXPATHLEN+1];
+static char exec_prefix[MAXPATHLEN+1];
+static char *module_search_path = NULL;
+static char lib_python[20]; /* Dynamically set to "lib/python" VERSION */
+
+static void
+reduce(dir)
+ char *dir;
+{
+ int i = strlen(dir);
+ while (i > 0 && dir[i] != SEP)
+ --i;
+ dir[i] = '\0';
+}
+
+
+static int
+exists(filename)
+ char *filename;
+{
+ struct stat buf;
+ return stat(filename, &buf) == 0;
+}
+
+
+static void
+join(buffer, stuff)
+ char *buffer;
+ char *stuff;
+{
+ int 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';
+}
+
+
+/* Make sure path ends in a slash.
+ * Assume path is MAXPATHLEN+1 sized buffer.
+ */
+static void
+string_addsep(path)
+ char *path;
+{
+ int len = strlen(path);
+
+ if (path[len-1] != SEP) {
+ path[len] = SEP;
+ if (len < MAXPATHLEN)
+ len++;
+ path[len] = '\0';
+ }
+}
+
+
+/* Append a source string onto the destination string, watching for
+ * buffer overruns. Assumes dest is MAXPATHLEN+1 sized buffer.
+ */
+static void
+string_append(dest, source)
+ char *dest;
+ char *source;
+{
+ int dlen = strlen(dest);
+ int slen = strlen(source);
+ int len = dlen + slen;
+
+ strncat(dest, source, MAXPATHLEN - dlen);
+ if (len < MAXPATHLEN)
+ len++;
+ dest[len] = '\0';
+}
+
+
+static int
+search_for_prefix(argv0_path, home)
+ char *argv0_path;
+ char *home;
+{
+ int i, n;
+ char *vpath;
+
+ /* Check VPATH to see if argv0_path is in the build directory.
+ * Complication: the VPATH passed in is relative to the
+ * Modules build directory and points to the Modules source
+ * directory; we need it relative to the build tree and
+ * pointing to the source tree. Solution: chop off a leading
+ * ".." (but only if it's there -- it could be an absolute
+ * path) and chop off the final component (assuming it's
+ * "Modules").
+ */
+ vpath = VPATH;
+ if (vpath[0] == '.' && vpath[1] == '.' && vpath[2] == '/')
+ vpath += 3;
+ strcpy(prefix, argv0_path);
+ join(prefix, vpath);
+ reduce(prefix);
+ join(prefix, "Lib");
+ join(prefix, LANDMARK);
+ if (exists(prefix))
+ return -1;
+
+ if (home) {
+ /* Check $PYTHONHOME */
+ char *delim;
+ strcpy(prefix, home);
+ delim = strchr(prefix, DELIM);
+ if (delim)
+ *delim = '\0';
+ join(prefix, lib_python);
+ join(prefix, LANDMARK);
+ if (exists(prefix))
+ return 1;
+ }
+
+ /* Search from argv0_path, until root is found */
+ strcpy(prefix, argv0_path);
+ do {
+ n = strlen(prefix);
+ join(prefix, lib_python);
+ join(prefix, LANDMARK);
+ if (exists(prefix))
+ return 1;
+ prefix[n] = '\0';
+ reduce(prefix);
+ } while (prefix[0]);
+
+ /* Look at configure's PREFIX */
+ strcpy(prefix, PREFIX);
+ join(prefix, lib_python);
+ join(prefix, LANDMARK);
+ if (exists(prefix))
+ return 1;
+
+ /* Look at `standard' directories */
+ for (i = 0; std_dirs[i]; i++) {
+ strcpy(prefix, std_dirs[i]);
+ join(prefix, lib_python);
+ join(prefix, LANDMARK);
+ if (exists(prefix))
+ return 1;
+ }
+ return 0;
+}
+
+
+static int
+search_for_exec_prefix(argv0_path, home)
+ char *argv0_path;
+ char *home;
+{
+ int i, n;
+
+ /* Check to see if argv[0] is in the build directory */
+ strcpy(exec_prefix, argv0_path);
+ join(exec_prefix, "Modules/Setup");
+ if (exists(exec_prefix)) {
+ reduce(exec_prefix);
+ return -1;
+ }
+
+ if (home) {
+ /* Check $PYTHONHOME */
+ char *delim;
+ delim = strchr(home, DELIM);
+ if (delim)
+ strcpy(exec_prefix, delim+1);
+ else
+ strcpy(exec_prefix, home);
+ join(exec_prefix, lib_python);
+ join(exec_prefix, "sharedmodules");
+ if (exists(exec_prefix))
+ return 1;
+ }
+
+ /* Search from argv0_path, until root is found */
+ strcpy(exec_prefix, argv0_path);
+ do {
+ n = strlen(exec_prefix);
+ join(exec_prefix, lib_python);
+ join(exec_prefix, "sharedmodules");
+ if (exists(exec_prefix))
+ return 1;
+ exec_prefix[n] = '\0';
+ reduce(exec_prefix);
+ } while (exec_prefix[0]);
+
+ /* Look at configure's EXEC_PREFIX */
+ strcpy(exec_prefix, EXEC_PREFIX);
+ join(exec_prefix, lib_python);
+ join(exec_prefix, "sharedmodules");
+ if (exists(exec_prefix))
+ return 1;
+
+ /* Look at `standard' directories */
+ for (i = 0; std_dirs[i]; i++) {
+ strcpy(exec_prefix, std_dirs[i]);
+ join(exec_prefix, lib_python);
+ join(exec_prefix, "sharedmodules");
+ if (exists(exec_prefix))
+ return 1;
+ }
+ return 0;
+}
+
+
+static void
+calculate_path()
+{
+ extern char *Py_GetProgramName();
+
+ char delimiter[2] = {DELIM, '\0'};
+ char separator[2] = {SEP, '\0'};
+ char *pythonpath = PYTHONPATH;
+ char *rtpypath = getenv("PYTHONPATH");
+ char *home = getenv("PYTHONHOME");
+ char *path = getenv("PATH");
+ char *prog = Py_GetProgramName();
+ char argv0_path[MAXPATHLEN+1];
+ char progpath[MAXPATHLEN+1];
+ int pfound, efound; /* 1 if found; -1 if found build directory */
+ char *buf;
+ int bufsz;
+ int prefixsz;
+ char *defpath = pythonpath;
+
+ /* Initialize this dynamically for K&R C */
+ sprintf(lib_python, "lib/python%s", VERSION);
+
+ /* If there is no slash in the argv0 path, then we have to
+ * assume python is on the user's $PATH, since there's no
+ * other way to find a directory to start the search from. If
+ * $PATH isn't exported, you lose.
+ */
+ if (strchr(prog, SEP))
+ strcpy(progpath, prog);
+ else if (path) {
+ while (1) {
+ char *delim = strchr(path, DELIM);
+
+ if (delim) {
+ int len = delim - path;
+ strncpy(progpath, path, len);
+ *(progpath + len) = '\0';
+ }
+ else
+ strcpy(progpath, path);
+
+ join(progpath, prog);
+ if (exists(progpath))
+ break;
+
+ if (!delim) {
+ progpath[0] = '\0';
+ break;
+ }
+ path = delim + 1;
+ }
+ }
+ else
+ progpath[0] = '\0';
+
+ strcpy(argv0_path, progpath);
+
+#if HAVE_READLINK
+ {
+ char tmpbuffer[MAXPATHLEN+1];
+ int linklen = readlink(progpath, tmpbuffer, MAXPATHLEN);
+ if (linklen != -1) {
+ /* It's not null terminated! */
+ tmpbuffer[linklen] = '\0';
+ if (tmpbuffer[0] == SEP)
+ strcpy(argv0_path, tmpbuffer);
+ else {
+ /* Interpret relative to progpath */
+ reduce(argv0_path);
+ join(argv0_path, tmpbuffer);
+ }
+ }
+ }
+#endif /* HAVE_READLINK */
+
+ reduce(argv0_path);
+
+ if (!(pfound = search_for_prefix(argv0_path, home))) {
+ fprintf(stderr,
+ "Could not find platform independent libraries <prefix>\n");
+ strcpy(prefix, PREFIX);
+ join(prefix, lib_python);
+ }
+ else
+ reduce(prefix);
+
+ if (!(efound = search_for_exec_prefix(argv0_path, home))) {
+ fprintf(stderr,
+ "Could not find platform dependent libraries <exec_prefix>\n");
+ strcpy(exec_prefix, EXEC_PREFIX);
+ join(exec_prefix, "lib/sharedmodules");
+ }
+ /* If we found EXEC_PREFIX do *not* reduce it! (Yet.) */
+
+ if (!pfound || !efound)
+ fprintf(stderr,
+ "Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]\n");
+
+ /* Calculate size of return buffer.
+ */
+ bufsz = 0;
+
+ if (rtpypath)
+ bufsz += strlen(rtpypath) + 1;
+
+ prefixsz = strlen(prefix) + 1;
+
+ while (1) {
+ char *delim = strchr(defpath, DELIM);
+
+ if (defpath[0] != SEP)
+ /* Paths are relative to prefix */
+ bufsz += prefixsz;
+
+ if (delim)
+ bufsz += delim - defpath + 1;
+ else {
+ bufsz += strlen(defpath) + 1;
+ break;
+ }
+ defpath = delim + 1;
+ }
+
+ bufsz += strlen(exec_prefix) + 1;
+
+ /* This is the only malloc call in this file */
+ buf = malloc(bufsz);
+
+ if (buf == NULL) {
+ /* We can't exit, so print a warning and limp along */
+ fprintf(stderr, "Not enough memory for dynamic PYTHONPATH.\n");
+ fprintf(stderr, "Using default static PYTHONPATH.\n");
+ module_search_path = PYTHONPATH;
+ }
+ else {
+ /* Run-time value of $PYTHONPATH goes first */
+ if (rtpypath) {
+ strcpy(buf, rtpypath);
+ strcat(buf, delimiter);
+ }
+
+ /* Next goes merge of compile-time $PYTHONPATH with
+ * dynamically located prefix.
+ */
+ defpath = pythonpath;
+ while (1) {
+ char *delim = strchr(defpath, DELIM);
+
+ if (defpath[0] != SEP) {
+ strcat(buf, prefix);
+ strcat(buf, separator);
+ }
+
+ if (delim) {
+ int len = delim - defpath + 1;
+ int end = strlen(buf) + len;
+ strncat(buf, defpath, len);
+ *(buf + end) = '\0';
+ }
+ else {
+ strcat(buf, defpath);
+ break;
+ }
+ defpath = delim + 1;
+ }
+ strcat(buf, delimiter);
+
+ /* Finally, on goes the directory for dynamic-load modules */
+ strcat(buf, exec_prefix);
+
+ /* And publish the results */
+ module_search_path = buf;
+ }
+
+ /* Reduce prefix and exec_prefix to their essence,
+ * e.g. /usr/local/lib/python1.5 is reduced to /usr/local.
+ * If we're loading relative to the build directory,
+ * return the compiled-in defaults instead.
+ */
+ if (pfound > 0) {
+ reduce(prefix);
+ reduce(prefix);
+ }
+ else
+ strcpy(prefix, PREFIX);
+
+ if (efound > 0) {
+ reduce(exec_prefix);
+ reduce(exec_prefix);
+ reduce(exec_prefix);
+ }
+ else
+ strcpy(exec_prefix, EXEC_PREFIX);
+}
+
+
+/* External interface */
char *
Py_GetPath()
{
- char *path = getenv("PYTHONPATH");
- char *defpath = PYTHONPATH;
- static char *buf = NULL;
- char *p;
- int n;
-
- if (path == NULL)
- path = "";
- n = strlen(path) + strlen(defpath) + 2;
- if (buf != NULL) {
- free(buf);
- buf = NULL;
- }
- buf = malloc(n);
- if (buf == NULL)
- Py_FatalError("not enough memory to copy module search path");
- strcpy(buf, path);
- p = buf + strlen(buf);
- if (p != buf)
- *p++ = DELIM;
- strcpy(p, defpath);
- return buf;
+ if (!module_search_path)
+ calculate_path();
+ return module_search_path;
}
-
-/* Similar for Makefile variables $prefix and $exec_prefix */
-
char *
Py_GetPrefix()
{
- return PREFIX;
+ if (!module_search_path)
+ calculate_path();
+ return prefix;
}
char *
Py_GetExecPrefix()
{
- return EXEC_PREFIX;
+ if (!module_search_path)
+ calculate_path();
+ return exec_prefix;
}