fix(linux): improved container support

ChangeLog

@@ -1,5 +1,7 @@
 2024-xx-xx v3.6.1
 
+  Improve support for Python processes running in containers.
+
   Bugfix: fixed a bug with the MOJO binary format that caused the line end
   position to wrongly be set to a non-zero value for CPython < 3.11, where line
   end information is not actually available.

src/linux/common.h

@@ -26,9 +26,11 @@
 #include <pthread.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <string.h>
 #include <sys/ptrace.h>
 
 #include "../error.h"
+#include "../hints.h"
 #include "../stats.h"
 
 
@@ -109,3 +111,24 @@ _procfs(pid_t pid, char * file) {
 
   return fp;
 }
+
+
+// ----------------------------------------------------------------------------
+static inline char *
+proc_root(pid_t pid, char * file) {
+  if (file[0] != '/') {
+    log_e("File path is not absolute");  // GCOV_EXCL_START
+    return NULL;  // GCOV_EXCL_STOP
+  }
+
+  char * proc_root = calloc(1, strlen(file) + 24);
+  if (!isvalid(proc_root))
+    return NULL;  // GCOV_EXCL_LINE
+
+  if (sprintf(proc_root, "/proc/%d/root%s", pid, file) < 0) {
+    free(proc_root);  // GCOV_EXCL_START
+    return NULL;  // GCOV_EXCL_STOP
+  }
+
+  return proc_root;
+}

src/linux/py_proc.h

@@ -455,16 +455,16 @@ _py_proc__parse_maps_file(py_proc_t * self) {
     // The first memory map of the executable
     if (!isvalid(pd->maps[MAP_BIN].path) && strcmp(pd->exe_path, pathname) == 0) {
       map = &(pd->maps[MAP_BIN]);
-      map->path = strndup(pathname, strlen(pathname));
+      map->path = proc_root(self->pid, pathname);
       if (!isvalid(map->path)) {
-        log_ie("Cannot duplicate path name");
+        log_e("Cannot get proc root path for %s", pathname);  // GCOV_EXCL_START
         set_error(EPROC);
-        FAIL;
+        FAIL;  // GCOV_EXCL_STOP
       }
-      map->file_size = _file_size(pathname);
+      map->file_size = _file_size(map->path);
       map->base = (void *) lower;
       map->size = upper - lower;
-      map->has_symbols = success(_py_proc__analyze_elf(self, pathname, (void *) lower));
+      map->has_symbols = success(_py_proc__analyze_elf(self, map->path, (void *) lower));
       if (map->has_symbols) {
         map->bss_base = self->map.bss.base;
         map->bss_size = self->map.bss.size;
@@ -479,13 +479,13 @@ _py_proc__parse_maps_file(py_proc_t * self) {
       int has_symbols = success(_py_proc__analyze_elf(self, pathname, (void *) lower));
       if (has_symbols) {
         map = &(pd->maps[MAP_LIBSYM]);
-        map->path = strndup(pathname, strlen(pathname));
+        map->path = proc_root(self->pid, pathname);
         if (!isvalid(map->path)) {
-          log_ie("Cannot duplicate path name");
+          log_e("Cannot get proc root path for %s", pathname);  // GCOV_EXCL_START
           set_error(EPROC);
-          FAIL;
+          FAIL;  // GCOV_EXCL_STOP
         }
-        map->file_size = _file_size(pathname);
+        map->file_size = _file_size(map->path);
         map->base = (void *) lower;
         map->size = upper - lower;
         map->has_symbols = TRUE;
@@ -503,13 +503,13 @@ _py_proc__parse_maps_file(py_proc_t * self) {
           unsigned int v;
           if (sscanf(needle, "libpython%u.%u", &v, &v) == 2) {
             map = &(pd->maps[MAP_LIBNEEDLE]);
-            map->path = needle_path = strndup(pathname, strlen(pathname));
+            map->path = needle_path = proc_root(self->pid, pathname);
             if (!isvalid(map->path)) {
-              log_ie("Cannot duplicate path name");
+              log_e("Cannot get proc root path for %s", pathname);  // GCOV_EXCL_START
               set_error(EPROC);
-              FAIL;
+              FAIL;  // GCOV_EXCL_STOP
             }
-            map->file_size = _file_size(pathname);
+            map->file_size = _file_size(map->path);
             map->base = (void *) lower;
             map->size = upper - lower;
             map->has_symbols = FALSE;

src/py_proc.c

@@ -110,17 +110,14 @@ _get_version_from_executable(char * binary, int * major, int * minor, int * patc
   #endif
 
   fp = _popen(cmd, "r");
-  if (!isvalid(fp)) {
-    set_error(EPROC);
+  if (!isvalid(fp))
     FAIL;
-  }
 
   while (fgets(version, sizeof(version) - 1, fp) != NULL) {
     if (sscanf(version, "Python %d.%d.%d", major, minor, patch) == 3)
       SUCCESS;
   }
 
-  set_error(EPROC);
   FAIL;
 } /* _get_version_from_executable */
 
@@ -129,37 +126,34 @@ _get_version_from_filename(char * filename, const char * needle, int * major, in
   #if defined PL_LINUX                                               /* LINUX */
   char         * base       = filename;
   char         * end        = base + strlen(base);
+  size_t         needle_len = strlen(needle);
 
   while (base < end) {
     base = strstr(base, needle);
     if (!isvalid(base)) {
       break;
     }
-    if (sscanf(base + strlen(needle), "%u.%u", major, minor) == 2) {
+    base += needle_len;
+    if (sscanf(base, "%u.%u", major, minor) == 2) {
       SUCCESS;
     }
   }
 
   #elif defined PL_WIN                                                 /* WIN */
   // Assume the library path is of the form *.python3[0-9]+[.]dll
   int n = strlen(filename);
-  if (n < 10) {
-    set_error(EPROC);
+  if (n < 10)
     FAIL;
-  }
 
   char * p = filename + n - 1;
   while (*(p--) != 'n' && p > filename);
   p++;
   *major = *(p++) - '0';
-  if (*major != 3) {
-    set_error(EPROC);
+  if (*major != 3)
     FAIL;
-  }
 
-  if (sscanf(p,"%d.dll", minor) == 1) {
+  if (sscanf(p,"%d.dll", minor) == 1)
     SUCCESS;
-  }
 
   #elif defined PL_MACOS                                               /* MAC */
   char * ver_needle = strstr(filename, "3.");
@@ -169,7 +163,6 @@ _get_version_from_filename(char * filename, const char * needle, int * major, in
 
   #endif
 
-  set_error(EPROC);
   FAIL;
 } /* _get_version_from_filename */