diff options
Diffstat (limited to 'gdb/linux-tdep.c')
| -rw-r--r-- | gdb/linux-tdep.c | 85 |
1 files changed, 44 insertions, 41 deletions
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c index 016aadf..1afa8d7 100644 --- a/gdb/linux-tdep.c +++ b/gdb/linux-tdep.c @@ -38,6 +38,7 @@ #include "gdbcmd.h" #include "gdb_regex.h" #include "common/enum-flags.h" +#include "common/gdb_optional.h" #include <ctype.h> @@ -493,6 +494,44 @@ decode_vmflags (char *p, struct smaps_vmflags *v) } } +/* Regexes used by mapping_is_anonymous_p. Put in a structure because + they're initialized lazily. */ + +struct mapping_regexes +{ + /* Matches "/dev/zero" filenames (with or without the "(deleted)" + string in the end). We know for sure, based on the Linux kernel + code, that memory mappings whose associated filename is + "/dev/zero" are guaranteed to be MAP_ANONYMOUS. */ + compiled_regex dev_zero + {"^/dev/zero\\( (deleted)\\)\\?$", REG_NOSUB, + _("Could not compile regex to match /dev/zero filename")}; + + /* Matches "/SYSV%08x" filenames (with or without the "(deleted)" + string in the end). These filenames refer to shared memory + (shmem), and memory mappings associated with them are + MAP_ANONYMOUS as well. */ + compiled_regex shmem_file + {"^/\\?SYSV[0-9a-fA-F]\\{8\\}\\( (deleted)\\)\\?$", REG_NOSUB, + _("Could not compile regex to match shmem filenames")}; + + /* A heuristic we use to try to mimic the Linux kernel's 'n_link == + 0' code, which is responsible to decide if it is dealing with a + 'MAP_SHARED | MAP_ANONYMOUS' mapping. In other words, if + FILE_DELETED matches, it does not necessarily mean that we are + dealing with an anonymous shared mapping. However, there is no + easy way to detect this currently, so this is the best + approximation we have. + + As a result, GDB will dump readonly pages of deleted executables + when using the default value of coredump_filter (0x33), while the + Linux kernel will not dump those pages. But we can live with + that. */ + compiled_regex file_deleted + {" (deleted)$", REG_NOSUB, + _("Could not compile regex to match '<file> (deleted)'")}; +}; + /* Return 1 if the memory mapping is anonymous, 0 otherwise. FILENAME is the name of the file present in the first line of the @@ -506,52 +545,16 @@ decode_vmflags (char *p, struct smaps_vmflags *v) static int mapping_is_anonymous_p (const char *filename) { - static regex_t dev_zero_regex, shmem_file_regex, file_deleted_regex; + static gdb::optional<mapping_regexes> regexes; static int init_regex_p = 0; if (!init_regex_p) { - struct cleanup *c = make_cleanup (null_cleanup, NULL); - /* Let's be pessimistic and assume there will be an error while compiling the regex'es. */ init_regex_p = -1; - /* DEV_ZERO_REGEX matches "/dev/zero" filenames (with or - without the "(deleted)" string in the end). We know for - sure, based on the Linux kernel code, that memory mappings - whose associated filename is "/dev/zero" are guaranteed to be - MAP_ANONYMOUS. */ - compile_rx_or_error (&dev_zero_regex, "^/dev/zero\\( (deleted)\\)\\?$", - _("Could not compile regex to match /dev/zero " - "filename")); - /* SHMEM_FILE_REGEX matches "/SYSV%08x" filenames (with or - without the "(deleted)" string in the end). These filenames - refer to shared memory (shmem), and memory mappings - associated with them are MAP_ANONYMOUS as well. */ - compile_rx_or_error (&shmem_file_regex, - "^/\\?SYSV[0-9a-fA-F]\\{8\\}\\( (deleted)\\)\\?$", - _("Could not compile regex to match shmem " - "filenames")); - /* FILE_DELETED_REGEX is a heuristic we use to try to mimic the - Linux kernel's 'n_link == 0' code, which is responsible to - decide if it is dealing with a 'MAP_SHARED | MAP_ANONYMOUS' - mapping. In other words, if FILE_DELETED_REGEX matches, it - does not necessarily mean that we are dealing with an - anonymous shared mapping. However, there is no easy way to - detect this currently, so this is the best approximation we - have. - - As a result, GDB will dump readonly pages of deleted - executables when using the default value of coredump_filter - (0x33), while the Linux kernel will not dump those pages. - But we can live with that. */ - compile_rx_or_error (&file_deleted_regex, " (deleted)$", - _("Could not compile regex to match " - "'<file> (deleted)'")); - /* We will never release these regexes, so just discard the - cleanups. */ - discard_cleanups (c); + regexes.emplace (); /* If we reached this point, then everything succeeded. */ init_regex_p = 1; @@ -573,9 +576,9 @@ mapping_is_anonymous_p (const char *filename) } if (*filename == '\0' - || regexec (&dev_zero_regex, filename, 0, NULL, 0) == 0 - || regexec (&shmem_file_regex, filename, 0, NULL, 0) == 0 - || regexec (&file_deleted_regex, filename, 0, NULL, 0) == 0) + || regexes->dev_zero.exec (filename, 0, NULL, 0) == 0 + || regexes->shmem_file.exec (filename, 0, NULL, 0) == 0 + || regexes->file_deleted.exec (filename, 0, NULL, 0) == 0) return 1; return 0; |