File crash-improve-find-extension.diff of Package crash

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File crash-improve-find-extension.diff of Package crash (Revision 885836cbd4ffe46065bae62e209a2fb0)

Currently displaying revision 885836cbd4ffe46065bae62e209a2fb0 , Show latest

From: Bernhard Walle <bwalle@suse.de>
Subject: Improve finding extension files
Patch-mainline: never

This patch adds /usr/lib{,64}/crash to the search path for extensions. This
allows extensions to be installed in that directories to confirm to the shared
library packaging policy of SUSE.

Also, improves the way error messages are printed.

Signed-off-by: Bernhard Walle <bwalle@suse.de>

---
 defs.h       |    1 
 extensions.c |  146 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-----
 symbols.c    |   27 ++++++++++
 3 files changed, 164 insertions(+), 10 deletions(-)

--- a/defs.h
+++ b/defs.h
@@ -3320,6 +3320,7 @@ void dump_symbol_table(void);
 void dump_struct_table(ulong);
 void dump_offset_table(char *, ulong);
 int is_elf_file(char *);
+int is_elf_file_silent(char *);
 int is_kernel(char *);
 int file_elf_version(char *);
 int is_system_map(char *);
--- a/extensions.c
+++ b/extensions.c
@@ -179,6 +179,136 @@ dump_extension_table(int verbose)
 	} while ((ext = ext->prev));
 }
 
+/**
+ * Tries to find the extension @p name. That function is called once with
+ * @p second_call set to @c false. When no extension is found, then the function
+ * is called again with @p second_call set to @c true. So the user doesn't get
+ * error messages when everything works, but he knows where crash searches for
+ * extensions when things go wrong.
+ *
+ * @param[in]  name the name of the extension to look for. That can be an
+ *             absolute path or just a file name. With or without the ".so"
+ *             extension
+ * @param[in]  second_call if set to @c true, then crash prints out where it
+ *             looks for extensions. But it doesn't print the error messages
+ *             to not get the same error messages twice.
+ * @param[out] buffer the buffer where the full path of the extension will
+ *             be copied to
+ * @param[in]  bufsiz the size of the buffer (should be PATH_MAX long)
+ *
+ * @return @c true if the extension was found (so buffer is true), @c false when
+ *         an error occurred
+ */
+int
+find_extension(const char *name, int second_call, char *buffer, size_t bufsiz)
+{
+	/* copy the supplied name into the buffer */
+	strncpy(buffer, name, bufsiz);
+	buffer[bufsiz-1] = 0;
+
+	/* check if the supplied buffer was large enough */
+	if (strlen(buffer) != strlen(name)) {
+		if (!second_call) {
+			error(WARNING, "find_extension(): Buffer too small"
+				" for %s\n", name);
+		}
+		return FALSE;
+	}
+
+	/* add .so if necessary */
+	if (strlen(buffer) <= 3 ||
+			strcmp(buffer + strlen(buffer) - 3, ".so") != 0) {
+
+		/* buffer still large enough */
+		if (strlen(buffer) + 3 > bufsiz) {
+			if (!second_call) {
+				error(WARNING, "Buffer too small for %s"
+					" when adding '.so' suffix", buffer);
+			}
+			return FALSE;
+		}
+
+		strcat(buffer, ".so");
+	}
+
+	if (second_call) {
+		fprintf(fp, "Trying to locate extension %s\n", buffer);
+	}
+
+	/*
+	 * When only a file name is given and not a path name, then we use
+	 * the search path to find extension
+	 */
+	if (strchr(buffer, '/') != NULL) {
+		char *canonical_path;
+
+		canonical_path = realpath(buffer, NULL);
+		if (!canonical_path) {
+			if (!second_call) {
+				error(WARNING, "%s does not exist\n", buffer);
+			}
+			return FALSE;
+		}
+
+		strncpy(buffer, canonical_path, bufsiz-1);
+		if (strlen(buffer) != strlen(canonical_path)) {
+			if (!second_call) {
+				error(WARNING, "find_extension(): "
+					"The supplied buffer is too small to "
+					"hold %s\n", canonical_path);
+			}
+			free(canonical_path);
+			return FALSE;
+		}
+		free (canonical_path);
+
+		if (is_elf_file_silent(buffer)) {
+			return TRUE;
+		} else {
+			if (!second_call) {
+				error(WARNING, "%s is not a valid extension"
+					" file", buffer);
+			}
+			return FALSE;
+		}
+        } else {
+		int i;
+		const char *search_paths[] = {
+			"/usr/lib/crash",
+			"/usr/lib64/crash"
+		};
+		const int path_no = sizeof(search_paths)/sizeof(const char *);
+		char *tmp = strdup(buffer);
+
+		for (i = 0; i < path_no; i++) {
+			const char *path = search_paths[i];
+
+			if (snprintf(buffer, bufsiz, "%s/%s", path, tmp)
+					>= bufsiz) {
+				error(WARNING, "find_extension(): The supplied "
+					"buffer is too small\n");
+				free(tmp);
+				return FALSE;
+			}
+
+			if (second_call) {
+				fprintf(fp, "Checking extension %s\n",
+					buffer);
+			}
+
+			if (is_elf_file_silent(buffer)) {
+				free(tmp);
+				return TRUE;
+			}
+		}
+		free(tmp);
+
+		if (!second_call) {
+			error(WARNING, "Unable to find extension %s\n", name);
+		}
+		return FALSE;
+	}
+}
 
 /*
  *  Load an extension library.
@@ -197,7 +327,7 @@ load_extension(char *lib)
 		}
 	}
 
-	size = sizeof(struct extension_table) + strlen(lib) + strlen("./") + 1;
+	size = sizeof(struct extension_table) + PATH_MAX + 1;
 
 	if ((ext = (struct extension_table *)malloc(size)) == NULL) 
 		error(FATAL, "cannot malloc extension_table space.");
@@ -205,15 +335,11 @@ load_extension(char *lib)
 	BZERO(ext, size);
 
 	ext->filename = (char *)((ulong)ext + sizeof(struct extension_table));
-	
-       /*
-	*  If the library is not specified by an absolute pathname, dlopen() 
-        *  does not look in the current directory.
-        */
-	if ((*lib != '.') && (*lib != '/') && is_elf_file(lib)) 
-		sprintf(ext->filename, "./%s", lib);
-	else
-		strcpy(ext->filename, lib);
+
+	if (!find_extension(lib, FALSE, ext->filename, PATH_MAX)) {
+		find_extension(lib, TRUE, ext->filename, PATH_MAX);
+		return;
+	}
 
        /*
         *  register_extension() will be called by the shared object's
--- a/symbols.c
+++ b/symbols.c
@@ -2520,6 +2520,33 @@ is_elf_file(char *s)
 }
 
 /*
+ * Version of is_elf_file that does't print errors.
+ */
+int
+is_elf_file_silent(char *s)
+{
+	int fd;
+	char magic[EI_NIDENT];
+
+	if ((fd = open(s, O_RDONLY)) < 0) {
+		return FALSE;
+	}
+	if (read(fd, magic, EI_NIDENT) != EI_NIDENT) {
+		close(fd);
+		return FALSE;
+	}
+	close(fd);
+
+	magic[EI_CLASS] = NULLCHAR;
+
+	if (!STREQ(magic, ELFMAG))
+		return FALSE;
+
+	return(is_bfd_format(s));
+}
+
+
+/*
  *  Verify a vmlinux file, issuing a warning for processor and endianness
  *  mismatches.
  */

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File crash-improve-find-extension.diff of Package crash (Revision 885836cbd4ffe46065bae62e209a2fb0)

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