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commit 3c3ae77e68a9032ef9f174bf6b1cc992b6a4cb35
Author: Pedro Alves <palves@redhat.com>
Date: Thu May 4 15:14:37 2017 +0100
Fix get_core_register_section leak, introduce thread_section_name
This plugs a leak introduced in the previous change to
get_core_register_section, which removed an xfree call that is
actually necessary because the 'section_name' local is static.
From [1] it looks like the reason the variable was made static to
begin with, was just "laziness" to avoid having to think about freeing
it on every function return path:
https://sourceware.org/ml/gdb-patches/2005-03/msg00237.html
The easiest to fix that nowadays is to use a std::string.
I don't see a need to xstrdup the section name in the single-threaded
case though, and also there's more than one place that computes a
multi-threaded section name in the same way. So put the section name
computation in a wrapper class with state.
gdb/ChangeLog:
2017-05-04 Pedro Alves <palves@redhat.com>
* corelow.c (thread_section_name): New class.
(get_core_register_section, get_core_siginfo): Use it.
diff --git gdb/corelow.c gdb/corelow.c
index 2266f2467a..0aff02d4db 100644
--- gdb/corelow.c
+++ gdb/corelow.c
@@ -485,6 +485,51 @@ core_detach (struct target_ops *ops, const char *args, int from_tty)
printf_filtered (_("No core file now.\n"));
}
+/* Build either a single-thread or multi-threaded section name for
+ PTID.
+
+ If ptid's lwp member is zero, we want to do the single-threaded
+ thing: look for a section named NAME (as passed to the
+ constructor). If ptid's lwp member is non-zero, we'll want do the
+ multi-threaded thing: look for a section named "NAME/LWP", where
+ LWP is the shortest ASCII decimal representation of ptid's lwp
+ member. */
+
+class thread_section_name
+{
+public:
+ /* NAME is the single-threaded section name. If PTID represents an
+ LWP, then the build section name is "NAME/LWP", otherwise it's
+ just "NAME" unmodified. */
+ thread_section_name (const char *name, ptid_t ptid)
+ {
+ if (ptid.lwp_p ())
+ {
+ m_storage = string_printf ("%s/%ld", name, ptid.lwp ());
+ m_section_name = m_storage.c_str ();
+ }
+ else
+ m_section_name = name;
+ }
+
+ /* Return the computed section name. The result is valid as long as
+ this thread_section_name object is live. */
+ const char *c_str () const
+ { return m_section_name; }
+
+ /* Disable copy. */
+ thread_section_name (const thread_section_name &) = delete;
+ void operator= (const thread_section_name &) = delete;
+
+private:
+ /* Either a pointer into M_STORAGE, or a pointer to the name passed
+ as parameter to the constructor. */
+ const char *m_section_name;
+ /* If we need to build a new section name, this is where we store
+ it. */
+ std::string m_storage;
+};
+
/* Try to retrieve registers from a section in core_bfd, and supply
them to core_vec->core_read_registers, as the register set numbered
WHICH.
@@ -511,21 +556,15 @@ get_core_register_section (struct regcache *regcache,
const char *human_name,
int required)
{
- static char *section_name;
struct bfd_section *section;
bfd_size_type size;
char *contents;
bool variable_size_section = (regset != NULL
&& regset->flags & REGSET_VARIABLE_SIZE);
- ptid_t ptid = regcache_get_ptid (regcache);
- if (ptid_get_lwp (ptid))
- section_name = xstrprintf ("%s/%ld", name,
- ptid_get_lwp (ptid));
- else
- section_name = xstrdup (name);
+ thread_section_name section_name (name, regcache->ptid ());
- section = bfd_get_section_by_name (core_bfd, section_name);
+ section = bfd_get_section_by_name (core_bfd, section_name.c_str ());
if (! section)
{
if (required)
@@ -537,13 +576,14 @@ get_core_register_section (struct regcache *regcache,
size = bfd_section_size (core_bfd, section);
if (size < min_size)
{
- warning (_("Section `%s' in core file too small."), section_name);
+ warning (_("Section `%s' in core file too small."),
+ section_name.c_str ());
return;
}
if (size != min_size && !variable_size_section)
{
warning (_("Unexpected size of section `%s' in core file."),
- section_name);
+ section_name.c_str ());
}
contents = (char *) alloca (size);
@@ -551,7 +591,7 @@ get_core_register_section (struct regcache *regcache,
(file_ptr) 0, size))
{
warning (_("Couldn't read %s registers from `%s' section in core file."),
- human_name, name);
+ human_name, section_name.c_str ());
return;
}
@@ -681,18 +721,8 @@ add_to_spuid_list (bfd *abfd, asection *asect, void *list_p)
static LONGEST
get_core_siginfo (bfd *abfd, gdb_byte *readbuf, ULONGEST offset, ULONGEST len)
{
- asection *section;
- char *section_name;
- const char *name = ".note.linuxcore.siginfo";
-
- if (ptid_get_lwp (inferior_ptid))
- section_name = xstrprintf ("%s/%ld", name,
- ptid_get_lwp (inferior_ptid));
- else
- section_name = xstrdup (name);
-
- section = bfd_get_section_by_name (abfd, section_name);
- xfree (section_name);
+ thread_section_name section_name (".note.linuxcore.siginfo", inferior_ptid);
+ asection *section = bfd_get_section_by_name (abfd, section_name.c_str ());
if (section == NULL)
return -1;
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