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Add OBJF_SYMS flag and use it to decide whether or not we have already

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tried to read symbols from a file, for mapped objfiles.  This fixes a
memory leak (actually a constant memory growth) due to reading symbol
files with no debug info and thus generating no psymtabs or symtabs.
Most typically happened with shared libraries.
This commit is contained in:
Fred Fish 1992-03-28 21:06:23 +00:00
parent c2e4669f8c
commit bf349b77fa
3 changed files with 60 additions and 51 deletions
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7
gdb/ChangeLog
View file

@ -1,3 +1,10 @@
Sat Mar 28 13:00:10 1992 Fred Fish (fnf@cygnus.com)
* objfiles.h (OBJF_SYMS): Define flag bit for objfile flags.
* symfile.c (symbol_file_add): Use OBJF_SYMS to decide whether
or not to try reading symbols from a mapped objfile. Plugs memory
leak due to shared libraries generating no psymtabs or symtabs.
Fri Mar 27 15:44:55 1992 John Gilmore (gnu at cygnus.com)
* buildsym.c (MAX_OF_C_TYPE, MIN_OF_C_TYPE): Unused, remove.

9
gdb/objfiles.h
View file

@ -236,6 +236,15 @@ struct objfile
#define OBJF_MAPPED (1 << 0) /* Objfile data is mmap'd */
/* When using mapped/remapped predigested gdb symbol information, we need
a flag that indicates that we have previously done an initial symbol
table read from this particular objfile. We can't just look for the
absence of any of the three symbol tables (msymbols, psymtab, symtab)
because if the file has no symbols for example, none of these will
exist. */
#define OBJF_SYMS (1 << 1) /* Have tried to read symbols */
/* The object file that the main symbol table was loaded from (e.g. the
argument to the "symbol-file" or "file" command). */

95
gdb/symfile.c
View file

@ -26,6 +26,7 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "target.h"
#include "value.h"
#include "symfile.h"
#include "objfiles.h"
#include "gdbcmd.h"
#include "breakpoint.h"
@ -39,16 +40,12 @@ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* Global variables owned by this file */
CORE_ADDR entry_point; /* Where execution starts in symfile */
int readnow_symbol_files; /* Read full symbols immediately */
/* External variables and functions referenced. */
extern int info_verbose;
extern CORE_ADDR startup_file_start; /* From blockframe.c */
extern CORE_ADDR startup_file_end; /* From blockframe.c */
/* Functions this file defines */
static void
@ -81,26 +78,6 @@ clear_symtab_users_once PARAMS ((void));
static struct sym_fns *symtab_fns = NULL;
/* When we need to allocate a new type, we need to know which type_obstack
to allocate the type on, since there is one for each objfile. The places
where types are allocated are deeply buried in function call hierarchies
which know nothing about objfiles, so rather than trying to pass a
particular objfile down to them, we just do an end run around them and
set current_objfile to be whatever objfile we expect to be using at the
time types are being allocated. For instance, when we start reading
symbols for a particular objfile, we set current_objfile to point to that
objfile, and when we are done, we set it back to NULL, to ensure that we
never put a type someplace other than where we are expecting to put it.
FIXME: Maybe we should review the entire type handling system and
see if there is a better way to avoid this problem. */
struct objfile *current_objfile = NULL;
/* The object file that the main symbol table was loaded from (e.g. the
argument to the "symbol-file" or "file" command). */
struct objfile *symfile_objfile = NULL;
/* Structures with which to manage partial symbol allocation. */
struct psymbol_allocation_list global_psymbols = {0}, static_psymbols = {0};
@ -328,6 +305,32 @@ psymtab_to_symtab (pst)
return pst->symtab;
}
/* Initialize entry point information for this objfile. */
void
init_entry_point_info (objfile)
struct objfile *objfile;
{
/* Save startup file's range of PC addresses to help blockframe.c
decide where the bottom of the stack is. */
if (bfd_get_file_flags (objfile -> obfd) & EXEC_P)
{
/* Executable file -- record its entry point so we'll recognize
the startup file because it contains the entry point. */
objfile -> ei.entry_point = bfd_get_start_address (objfile -> obfd);
}
else
{
/* Examination of non-executable.o files. Short-circuit this stuff. */
/* ~0 will not be in any file, we hope. */
objfile -> ei.entry_point = ~0;
/* set the startup file to be an empty range. */
objfile -> ei.entry_file_lowpc = 0;
objfile -> ei.entry_file_highpc = 0;
}
}
/* Process a symbol file, as either the main file or as a dynamically
loaded file.
@ -352,30 +355,19 @@ syms_from_objfile (objfile, addr, mainline, verbo)
/* There is a distinction between having no symbol table
(we refuse to read the file, leaving the old set of symbols around)
and having no debugging symbols in your symbol table (we read
the file and end up with a mostly empty symbol table). */
the file and end up with a mostly empty symbol table).
FIXME: This strategy works correctly when the debugging symbols are
intermixed with "normal" symbols. However, when the debugging symbols
are separate, such as with ELF/DWARF, it is perfectly plausible for
the symbol table to be missing but still have all the DWARF info
intact. Thus in general it is wrong to assume that having no symbol
table implies no debugging information. */
if (!(bfd_get_file_flags (objfile -> obfd) & HAS_SYMS))
return;
/* Save startup file's range of PC addresses to help blockframe.c
decide where the bottom of the stack is. */
if (bfd_get_file_flags (objfile -> obfd) & EXEC_P)
{
/* Executable file -- record its entry point so we'll recognize
the startup file because it contains the entry point. */
entry_point = bfd_get_start_address (objfile -> obfd);
}
else
{
/* Examination of non-executable.o files. Short-circuit this stuff. */
/* ~0 will not be in any file, we hope. */
entry_point = ~0;
/* set the startup file to be an empty range. */
startup_file_start = 0;
startup_file_end = 0;
}
init_entry_point_info (objfile);
find_sym_fns (objfile);
if (mainline)
@ -488,11 +480,12 @@ symbol_file_add (name, from_tty, addr, mainline, mapped, readnow)
/* If the objfile uses a mapped symbol file, and we have a psymtab for
it, then skip reading any symbols at this time. */
if ((objfile -> flags & OBJF_MAPPED) && (objfile -> psymtabs != NULL))
if ((objfile -> flags & OBJF_MAPPED) && (objfile -> flags & OBJF_SYMS))
{
/* We mapped in an existing symbol table file that already has had
the psymbols read in. So we can skip that part. Notify the user
that instead of reading the symbols, they have been mapped. */
initial symbol reading performed, so we can skip that part. Notify
the user that instead of reading the symbols, they have been mapped.
*/
if (from_tty || info_verbose)
{
printf_filtered ("Mapped symbols for %s...", name);
@ -503,8 +496,8 @@ symbol_file_add (name, from_tty, addr, mainline, mapped, readnow)
else
{
/* We either created a new mapped symbol table, mapped an existing
symbol table file with no partial symbols, or need to read an
unmapped symbol table. */
symbol table file which has not had initial symbol reading
performed, or need to read an unmapped symbol table. */
if (from_tty || info_verbose)
{
printf_filtered ("Reading symbols from %s...", name);
@ -512,6 +505,7 @@ symbol_file_add (name, from_tty, addr, mainline, mapped, readnow)
fflush (stdout);
}
syms_from_objfile (objfile, addr, mainline, from_tty);
objfile -> flags |= OBJF_SYMS;
}
/* We now have at least a partial symbol table. Check to see if the
@ -519,8 +513,7 @@ symbol_file_add (name, from_tty, addr, mainline, mapped, readnow)
the gdb startup command line or on a per symbol file basis. Expand
all partial symbol tables for this objfile if so. */
readnow |= readnow_symbol_files;
if (readnow)
if (readnow || readnow_symbol_files)
{
if (from_tty || info_verbose)
{