[ltrace-commits] 01/13: We now use known prototypes for all aliased symbols (same address)
Petr Machata
pmachata-guest at moszumanska.debian.org
Fri Jul 25 11:05:29 UTC 2014
This is an automated email from the git hooks/post-receive script.
pmachata-guest pushed a commit to branch master
in repository ltrace.
commit f781aa335251eb4166d2609764d039346636c207
Author: Dima Kogan <dima at secretsauce.net>
Date: Mon Jun 2 02:01:57 2014 -0700
We now use known prototypes for all aliased symbols (same address)
Some libraries have multiple names for the same function. Prior to this patch,
it was possible to define a prototype for a symbol, and not have ltrace use it
because it saw a different symbol be called. libc is a common source of this.
For instance (on my amd64 Debian box) it defines the nanosleep symbol as both
'nanosleep' and '__GI___nanosleep', at the same address. If a calling library
calls '__GI___nanosleep', then an ltrace prototype for 'nanosleep' would not be
used, even though it should apply to this call
---
dwarf_prototypes.c | 7 +-
library.c | 241 ++++++++++++++++++++++++++++++++++++++++++++++-------
library.h | 58 +++++++++++--
ltrace-elf.c | 25 ++----
output.c | 39 ++++++++-
proc.c | 52 +++++++++---
6 files changed, 346 insertions(+), 76 deletions(-)
diff --git a/dwarf_prototypes.c b/dwarf_prototypes.c
index 6094658..b50c82e 100644
--- a/dwarf_prototypes.c
+++ b/dwarf_prototypes.c
@@ -910,12 +910,7 @@ static bool import_subprogram(struct protolib *plib, struct library *lib,
{
// I use the linkage function name if there is one, otherwise the
// plain name
- const char *function_name = NULL;
- Dwarf_Attribute attr;
- if (dwarf_attr(die, DW_AT_linkage_name, &attr) != NULL)
- function_name = dwarf_formstring(&attr);
- if (function_name == NULL)
- function_name = dwarf_diename(die);
+ const char *function_name = dwarf_diename(die);
if (function_name == NULL) {
complain(die, "Function has no name. Not importing");
return true;
diff --git a/library.c b/library.c
index 3a22519..7ccd7da 100644
--- a/library.c
+++ b/library.c
@@ -29,8 +29,12 @@
#include "callback.h"
#include "debug.h"
#include "dict.h"
+#include "vect.h"
#include "backend.h" // for arch_library_symbol_init, arch_library_init
+static void
+library_exported_names_init(struct library_exported_names *names);
+
#ifndef OS_HAVE_LIBRARY_DATA
int
os_library_init(struct library *lib)
@@ -292,7 +296,7 @@ private_library_init(struct library *lib, enum library_type type)
lib->own_pathname = 0;
lib->symbols = NULL;
- lib->exported_names = NULL;
+ library_exported_names_init(&lib->exported_names);
lib->type = type;
#if defined(HAVE_LIBDW)
@@ -316,18 +320,213 @@ library_init(struct library *lib, enum library_type type)
return 0;
}
-static int
-library_exported_name_clone(struct library_exported_name *retp,
- struct library_exported_name *exnm)
+
+
+
+
+static void _dtor_string(const char **tgt, void *data)
+{
+ free((char*)*tgt);
+}
+static int _clone_vect(struct vect **to, const struct vect **from, void *data)
+{
+ *to = malloc(sizeof(struct vect));
+ if(*to == NULL)
+ return -1;
+
+ return
+ VECT_CLONE(*to, *from, const char*,
+ dict_clone_string,
+ _dtor_string,
+ NULL);
+}
+static void _dtor_vect(const struct vect **tgt, void *data)
+{
+ VECT_DESTROY(*tgt, const char*, _dtor_string, NULL);
+ free(*tgt);
+}
+
+static void
+library_exported_names_init(struct library_exported_names *names)
+{
+ DICT_INIT(&names->names,
+ const char*, uint64_t,
+ dict_hash_string, dict_eq_string, NULL);
+ DICT_INIT(&names->addrs,
+ uint64_t, struct vect*,
+ dict_hash_uint64, dict_eq_uint64, NULL);
+}
+
+static void
+library_exported_names_destroy(struct library_exported_names *names)
{
- char *name = exnm->own_name ? strdup(exnm->name) : (char *)exnm->name;
- if (name == NULL)
+ DICT_DESTROY(&names->names,
+ const char*, uint64_t,
+ _dtor_string, NULL, NULL);
+ DICT_DESTROY(&names->addrs,
+ uint64_t, struct vect*,
+ NULL, _dtor_vect, NULL);
+}
+
+static int
+library_exported_names_clone(struct library_exported_names *retp,
+ const struct library_exported_names *names)
+{
+ return
+ DICT_CLONE(&retp->names, &names->names,
+ const char*, uint64_t,
+ dict_clone_string, _dtor_string,
+ NULL, NULL,
+ NULL) ||
+ DICT_CLONE(&retp->addrs, &names->addrs,
+ uint64_t, struct vect*,
+ NULL, NULL,
+ _clone_vect, _dtor_vect,
+ NULL);
+}
+
+int library_exported_names_push(struct library_exported_names *names,
+ uint64_t addr, const char *name,
+ int own_name )
+{
+ // first, take ownership of the name, if it's not yet ours
+ if(!own_name)
+ name = strdup(name);
+ if(name == NULL)
return -1;
- retp->name = name;
- retp->own_name = exnm->own_name;
+
+ // push to the name->addr map
+ int result = DICT_INSERT(&names->names, &name, &addr);
+ if(result == 1) {
+ // This symbol is already present in the table. This library has
+ // multiple copies of this symbol (probably corresponding to
+ // different symbol versions). I should handle this gracefully
+ // at some point, but for now I simply ignore later instances of
+ // any particular symbol
+ free(name);
+ return 0;
+ }
+
+ if(result != 0)
+ return result;
+
+ // push to the addr->names map
+ // I get the alias vector. If it doesn't yet exist, I make it
+ struct vect *aliases;
+ struct vect **paliases = DICT_FIND_REF(&names->addrs,
+ &addr, struct vect*);
+
+ if (paliases == NULL) {
+ aliases = malloc(sizeof(struct vect));
+ if(aliases == NULL)
+ return -1;
+ VECT_INIT(aliases, const char*);
+ result = DICT_INSERT(&names->addrs, &addr, &aliases);
+ if(result != 0)
+ return result;
+ }
+ else
+ aliases = *paliases;
+
+ const char *namedup = strdup(name);
+ if(namedup == NULL)
+ return -1;
+
+ result = vect_pushback(aliases, &namedup);
+ if(result != 0)
+ return result;
+
return 0;
}
+struct library_exported_names_each_context
+{
+ enum callback_status (*inner_cb)(const char *, void *);
+ void *data;
+ bool failure : 1;
+};
+static enum callback_status
+library_exported_names_each_cb(const char **key, uint64_t *value, void *data)
+{
+ struct library_exported_names_each_context *context =
+ (struct library_exported_names_each_context*)data;
+ enum callback_status status = context->inner_cb(*key, context->data);
+ if(status == CBS_FAIL)
+ context->failure = true;
+ return status;
+}
+bool library_exported_names_each(const struct library_exported_names *names,
+ enum callback_status (*cb)(const char *,
+ void *),
+ void *data)
+{
+ struct library_exported_names_each_context context =
+ {.inner_cb = cb,
+ .data = data,
+ .failure = false};
+ DICT_EACH(&names->names,
+ const char*, uint64_t,
+ NULL, library_exported_names_each_cb, &context);
+ return !context.failure;
+}
+
+struct library_exported_names_each_alias_context
+{
+ enum callback_status (*inner_cb)(const char *, void *);
+ const char *origname;
+ void *data;
+ bool failure : 1;
+};
+static enum callback_status
+library_exported_names_each_alias_cb(const char **name, void *data)
+{
+ struct library_exported_names_each_alias_context *context =
+ (struct library_exported_names_each_alias_context*)data;
+
+ // I do not report the original name we were asked about. Otherwise, any
+ // time the caller asks for aliases of symbol "sym", I'll always report
+ // "sym" along with any actual aliases
+ if(strcmp(*name, context->origname) == 0)
+ return CBS_CONT;
+
+ enum callback_status status = context->inner_cb(*name, context->data);
+ if(status == CBS_FAIL)
+ context->failure = true;
+ return status;
+}
+
+bool library_exported_names_each_alias(
+ const struct library_exported_names *names,
+ const char *aliasname,
+ enum callback_status (*cb)(const char *,
+ void *),
+ void *data)
+{
+ // I have a symbol name. I look up its address, then get the list of
+ // aliased names
+ uint64_t *addr = DICT_FIND_REF(&names->names,
+ &aliasname, uint64_t);
+ if(addr == NULL)
+ return false;
+
+ // OK. I have an address. Get the list of symbols at this address
+ struct vect **aliases = DICT_FIND_REF(&names->addrs,
+ addr, struct vect*);
+ if(aliases == NULL)
+ return false;
+
+ struct library_exported_names_each_alias_context context =
+ {.inner_cb = cb,
+ .origname = aliasname,
+ .data = data,
+ .failure = false};
+ VECT_EACH(*aliases, const char*, NULL,
+ library_exported_names_each_alias_cb, &context);
+}
+
+
+
+
int
library_clone(struct library *retp, struct library *lib)
{
@@ -372,20 +571,9 @@ library_clone(struct library *retp, struct library *lib)
}
/* Clone exported names. */
- {
- struct library_exported_name *it;
- struct library_exported_name **nnamep = &retp->exported_names;
- for (it = lib->exported_names; it != NULL; it = it->next) {
- *nnamep = malloc(sizeof(**nnamep));
- if (*nnamep == NULL
- || library_exported_name_clone(*nnamep, it) < 0) {
- free(*nnamep);
- goto fail;
- }
- nnamep = &(*nnamep)->next;
- }
- *nnamep = NULL;
- }
+ if (library_exported_names_clone(&retp->exported_names,
+ &lib->exported_names) != 0)
+ goto fail;
if (os_library_clone(retp, lib) < 0)
goto fail;
@@ -419,14 +607,7 @@ library_destroy(struct library *lib)
}
/* Release exported names. */
- struct library_exported_name *it;
- for (it = lib->exported_names; it != NULL; ) {
- struct library_exported_name *next = it->next;
- if (it->own_name)
- free((char *)it->name);
- free(it);
- it = next;
- }
+ library_exported_names_destroy(&lib->exported_names);
}
void
diff --git a/library.h b/library.h
index 4d649e0..f8a5cf8 100644
--- a/library.h
+++ b/library.h
@@ -23,11 +23,13 @@
#define _LIBRARY_H_
#include <stdint.h>
+#include <stdbool.h>
#if defined(HAVE_LIBDW)
# include <elfutils/libdwfl.h>
#endif
+#include "dict.h"
#include "callback.h"
#include "forward.h"
#include "sysdep.h"
@@ -41,11 +43,21 @@ enum toplt {
size_t arch_addr_hash(const arch_addr_t *addr);
int arch_addr_eq(const arch_addr_t *addr1, const arch_addr_t *addr2);
-/* For handling -l. */
-struct library_exported_name {
- struct library_exported_name *next;
- const char *name;
- int own_name : 1;
+
+/* For handling -l and for handling library export aliases (different symbol
+ * name, same address)
+ *
+ * This structure needs to
+ * - store (addr, name) tuples
+ * - be searchable by addr (when populating)
+ * - be searchable by name (when looking for aliases)
+ * - be enumeratable (by activate_latent_in())
+ */
+struct library_exported_names {
+ // I store the data in several structures to facilitate different types
+ // of access
+ struct dict names; // maps a name to an address
+ struct dict addrs; // maps an address to a vect of names
};
struct library_symbol {
@@ -158,8 +170,10 @@ struct library {
/* List of names that this library implements, and that match
* -l filter. Each time a new library is mapped, its list of
* exports is examined, and corresponding PLT slots are
- * enabled. */
- struct library_exported_name *exported_names;
+ * enabled. This data structure also keeps track of export
+ * addresses to find symbols with different names, but same
+ * addresses */
+ struct library_exported_names exported_names;
/* Prototype library associated with this library. */
struct protolib *protolib;
@@ -241,4 +255,34 @@ int arch_translate_address(struct ltelf *lte,
int arch_translate_address_dyn(struct process *proc,
arch_addr_t addr, arch_addr_t *ret);
+
+/* Pushes a name/address tuple to the list of a library's exports. Returns 0 on
+ * success
+ */
+int library_exported_names_push(struct library_exported_names *names,
+ uint64_t addr, const char *name,
+ int own_name );
+
+/* Iterates through the a library's export list. The callback is called for
+ * every symbol a library exports. Symbol aliases do not apply here. If multiple
+ * symbols are defined at the same address, each is reported here. Returns true
+ * on success. If the callback fails at any point, this returns false
+ */
+bool library_exported_names_each(const struct library_exported_names *names,
+ enum callback_status (*cb)(const char *,
+ void *),
+ void *data);
+
+/* Iterates through the a library's export list, reporting each symbol that is
+ * an alias of the given 'aliasname' symbol. This 'aliasname' symbol itself is
+ * NOT reported, so if this symbol is unique, the callback is not called at all.
+ * Returns true on success
+ */
+bool library_exported_names_each_alias(
+ const struct library_exported_names *names,
+ const char *aliasname,
+ enum callback_status (*cb)(const char *,
+ void *),
+ void *data);
+
#endif /* _LIBRARY_H_ */
diff --git a/ltrace-elf.c b/ltrace-elf.c
index f638342..a6a5531 100644
--- a/ltrace-elf.c
+++ b/ltrace-elf.c
@@ -901,13 +901,8 @@ static int
populate_this_symtab(struct process *proc, const char *filename,
struct ltelf *lte, struct library *lib,
Elf_Data *symtab, const char *strtab, size_t count,
- struct library_exported_name **names)
+ struct library_exported_names *names)
{
- /* If a valid NAMES is passed, we pass in *NAMES a list of
- * symbol names that this library exports. */
- if (names != NULL)
- *names = NULL;
-
/* Using sorted array would be arguably better, but this
* should be well enough for the number of symbols that we
* typically deal with. */
@@ -957,20 +952,14 @@ populate_this_symtab(struct process *proc, const char *filename,
/* If we are interested in exports, store this name. */
if (names != NULL) {
- struct library_exported_name *export
- = malloc(sizeof *export);
char *name_copy = strdup(name);
-
- if (name_copy == NULL || export == NULL) {
- free(name_copy);
- free(export);
+ if (name_copy == NULL ||
+ library_exported_names_push(names,
+ sym.st_value,
+ name_copy, 1) != 0)
+ {
fprintf(stderr, "Couldn't store symbol %s. "
"Tracing may be incomplete.\n", name);
- } else {
- export->name = name_copy;
- export->own_name = 1;
- export->next = *names;
- *names = export;
}
}
@@ -1115,7 +1104,7 @@ populate_symtab(struct process *proc, const char *filename,
/* Check whether we want to trace symbols implemented by this
* library (-l). */
- struct library_exported_name **names = NULL;
+ struct library_exported_names *names = NULL;
if (exports) {
debug(DEBUG_FUNCTION, "-l matches %s", lib->soname);
names = &lib->exported_names;
diff --git a/output.c b/output.c
index 10faee2..2128816 100644
--- a/output.c
+++ b/output.c
@@ -197,6 +197,28 @@ snip_period(char *buf)
}
}
+struct lookup_prototype_alias_context
+{
+ struct library *lib;
+ struct prototype *result; // output
+};
+static enum callback_status
+lookup_prototype_alias_cb(const char *name, void *data)
+{
+ struct lookup_prototype_alias_context *context =
+ (struct lookup_prototype_alias_context*)data;
+
+ struct library *lib = context->lib;
+
+ context->result =
+ protolib_lookup_prototype(lib->protolib, name,
+ lib->type != LT_LIBTYPE_SYSCALL);
+ if (context->result != NULL)
+ return CBS_STOP;
+
+ return CBS_CONT;
+}
+
static struct prototype *
library_get_prototype(struct library *lib, const char *name)
{
@@ -235,8 +257,21 @@ library_get_prototype(struct library *lib, const char *name)
if (lib->protolib == NULL)
return NULL;
- return protolib_lookup_prototype(lib->protolib, name,
- lib->type != LT_LIBTYPE_SYSCALL);
+ struct prototype *result =
+ protolib_lookup_prototype(lib->protolib, name,
+ lib->type != LT_LIBTYPE_SYSCALL);
+ if (result != NULL)
+ return result;
+
+ // prototype not found. Is it aliased?
+ struct lookup_prototype_alias_context context = {.lib = lib,
+ .result = NULL};
+ library_exported_names_each_alias(&lib->exported_names, name,
+ lookup_prototype_alias_cb,
+ &context);
+
+ // if found, the prototype is stored here, otherwise it's NULL
+ return context.result;
}
struct find_proto_data {
diff --git a/proc.c b/proc.c
index 5385510..6d6562f 100644
--- a/proc.c
+++ b/proc.c
@@ -867,23 +867,49 @@ proc_activate_delayed_symbol(struct process *proc,
return breakpoint_for_symbol(libsym, proc);
}
+
+struct activate_latent_in_context
+{
+ struct process *proc;
+ struct library *lib;
+};
static enum callback_status
-activate_latent_in(struct process *proc, struct library *lib, void *data)
+activate_latent_in_cb(const char *name, void *data)
{
- struct library_exported_name *exported;
- for (exported = data; exported != NULL; exported = exported->next) {
- struct library_symbol *libsym = NULL;
- while ((libsym = library_each_symbol(lib, libsym,
- library_symbol_named_cb,
- (void *)exported->name))
- != NULL)
- if (libsym->latent
- && proc_activate_latent_symbol(proc, libsym) < 0)
- return CBS_FAIL;
- }
+ const struct activate_latent_in_context *ctx =
+ (const struct activate_latent_in_context*)data;
+
+ struct process *proc = ctx->proc;
+ struct library *lib = ctx->lib;
+
+ struct library_symbol *libsym = NULL;
+ while ((libsym = library_each_symbol(lib, libsym,
+ library_symbol_named_cb,
+ (void *)name))
+ != NULL)
+ if (libsym->latent
+ && proc_activate_latent_symbol(proc, libsym) < 0)
+ return CBS_FAIL;
+
return CBS_CONT;
}
+static enum callback_status
+activate_latent_in(struct process *proc, struct library *lib, void *data)
+{
+ struct library_exported_names *exported_names =
+ (struct library_exported_names*)data;
+
+ struct activate_latent_in_context context = {.proc = proc,
+ .lib = lib};
+ if (library_exported_names_each(exported_names,
+ activate_latent_in_cb,
+ &context))
+ return CBS_CONT;
+ else
+ return CBS_FAIL;
+}
+
void
proc_add_library(struct process *proc, struct library *lib)
{
@@ -969,7 +995,7 @@ proc_add_library(struct process *proc, struct library *lib)
* library itself). */
struct library *lib2 = NULL;
while ((lib2 = proc_each_library(proc, lib2, activate_latent_in,
- lib->exported_names)) != NULL)
+ &lib->exported_names)) != NULL)
fprintf(stderr,
"Couldn't activate latent symbols for %s in %d: %s.\n",
lib2->soname, proc->pid, strerror(errno));
--
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