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core - core image file
DESCRIPTION
The operating system writes out a core image of a process
when it is terminated due to the receipt of some signals.
The core image is called core and is written in the
process's working directory (provided it can be; normal
access controls apply). A process with an effective user ID
different from the real user ID will not produce a core
image.
The core file contains all the process information pertinent
to debugging: contents of hardware registers, process
status, and process data. The format of a core file is
object file specific.
For ELF executable programs (see a.out(4)), the core file
generated is also an ELF file, containing ELF program and
file headers. The e_type field in the file header has type
ET_CORE. The program header contains an entry for every seg-
ment that was part of the process address space, including
shared library segments. The contents of the writable seg-
ments are also part of the core image.
The program header of an ELF core file also contains entries
for two NOTE segments, each containing several note entries
as described below. The note entry header and core file note
type (n_type) definitions are contained in . The
first NOTE segment exists for binary compatibility with old
programs that deal with core files. It contains structures
defined in . New programs should recognize
and skip this NOTE segment, advancing instead to the new
NOTE segment. The old NOTE segment will be deleted from core
files in a future release.
The old NOTE segment contains the following entries. Each
has entry name "CORE" and presents the contents of a system
structure:
prpsinfo_t
n_type : NT_PRPSINFO. This entry contains informa-
tion of interest to the ps(1) command, such as
process status, CPU usage, "nice" value, control-
ling terminal, user-ID, process-ID, the name of
the executable, and so forth. The prpsinfo_t
structure is defined in .
char array
n_type: NT_PLATFORM. This entry contains a string
describing the specific model of the hardware
platform on which this core file was created. This
information is the same as provided by sysinfo(2)
when invoked with the command SI_PLATFORM.
auxv_t array
n_type: NT_AUXV. This entry contains the array of
auxv_t structures that was passed by the operating
system as startup information to the dynamic
linker. Auxiliary vector information is defined
in .
Following these entries, for each light-weight process (LWP)
in the process, the old NOTE segment contains an entry with
a prstatus_t structure, plus other optionally-present
entries describing the LWP, as follows:
prstatus_t
n_type: NT_PRSTATUS. This structure contains
things of interest to a debugger from the operat-
ing system, such as the general registers, signal
dispositions, state, reason for stopping,
process-ID, and so forth. The prstatus_t structure
is defined in .
prfpregset_t
n_type: NT_PRFPREG. This entry is present only if
the LWP used the floating-point hardware. It con-
tains the floating-point registers. The
prfpregset_t structure is defined in
.
gwindows_t
n_type: NT_GWINDOWS. This entry is present only on
a SPARC machine and only if the system was unable
to flush all of the register windows to the stack.
It contains all of the unspilled register windows.
The gwindows_t structure is defined in
.
prxregset_t
n_type: NT_PRXREG. This entry is present only if
the machine has extra register state associated
with it. It contains the extra register state. The
prxregset_t structure is defined in
.
The new NOTE segment contains the following entries. Each
has entry name "CORE" and presents the contents of a system
structure:
psinfo_t n_type: NT_PSINFO. This structure contains infor-
mation of interest to the ps(1) command, such as
process status, CPU usage, "nice" value,
controlling terminal, user-ID, process-ID, the
name of the executable, and so forth. The psinfo_t
structure is defined in .
pstatus_t n_type: NT_PSTATUS. This structure contains things
of interest to a debugger from the operating sys-
tem, such as pending signals, state, process-ID,
and so forth. The pstatus_t structure is defined
in .
char array
n_type: NT_PLATFORM. This entry contains a string
describing the specific model of the hardware
platform on which this core file was created. This
information is the same as provided by sysinfo(2)
when invoked with the command SI_PLATFORM.
auxv_t array
n_type: NT_AUXV. This entry contains the array of
auxv_t structures that was passed by the operating
system as startup information to the dynamic
linker. Auxiliary vector information is defined
in .
Following these entries, for each LWP in the process, the
new NOTE segment contains an entry with an lwpsinfo_t struc-
ture plus an entry with an lwpstatus_t structure, plus other
optionally-present entries describing the LWP, as follows:
lwpsinfo_t
n_type: NT_LWPSINFO. This structure contains
information of interest to the ps(1) command, such
as LWP status, CPU usage, "nice" value, LWP-ID,
and so forth. The lwpsinfo_t structure is defined
in .
lwpstatus_t
n_type: NT_LWPSTATUS. This structure contains
things of interest to a debugger from the operat-
ing system, such as the general registers, the
floating point registers, state, reason for stop-
ping, LWP-ID, and so forth. The lwpstatus_t struc-
ture is defined in .
gwindows_t
n_type: NT_GWINDOWS. This entry is present only on
a SPARC machine and only if the system was unable
to flush all of the register windows to the stack.
It contains all of the unspilled register windows.
The gwindows_t structure is defined in
.
prxregset_t
n_type: NT_PRXREG. This entry is present only if
the machine has extra register state associated
with it. It contains the extra register state. The
prxregset_t structure is defined in
.
asrset_t n_type: NT_ASRS. This entry is present only on a
SPARC V9 machine and only if the process is a 64-
bit process. It contains the ancillary state
registers for the LWP. The asrset_t structure is
defined in .
The size of the core file created by a process may be con-
trolled by the user (see getrlimit(2)).
SEE ALSO
adb(1), gcore(1), ps(1), crash(1M), getrlimit(2), setuid(2),
sysinfo(2), elf(3E), a.out(4), proc(4), signal(5)
ANSI C Programmer's Guide
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