core - format of memory image file

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SYNOPSIS

DESCRIPTION

The operating system writes out a memory image of a terminated process when any of various errors occur. See sigvec.2 for the list of reasons; the most common are memory violations, illegal instructions, bus errors, and user-generated quit signals. The memory image is called core and is written in the process's working directory (provided it can be; normal access controls apply). Set-user-ID and set-group-ID programs do not produce core files when they terminate as this would cause a security loophole.

The maximum size of a core file is limited by setrlimit (see getrlimit.2 Files which would be larger than the limit are not created.

The core file consists of a core structure, as defined in the <sys/core.h> file, followed by the data pages and then the stack pages of the process image. The core structure includes the program's header, the size of the text, data, and stack segments, the name of the program and the number of the signal that terminated the process. The program's header is described by the exec structure defined in the <sys/exec.h> file, except on Sun386i systems.

struct core {
	int	c_magic;		/* Corefile magic number */
	int	c_len;			/* Sizeof (struct core) */
	struct	regs c_regs;		/* General purpose registers */
	struct 	exec c_aouthdr;		/* A.out header */
	int	c_signo;		/* Killing signal, if any */
	int	c_tsize;		/* Text size (bytes) */
	int	c_dsize;		/* Data size (bytes) */
	int	c_ssize;		/* Stack size (bytes) */
	char	c_cmdname[CORE_NAMELEN + 1]; /* Command name */
	struct	fpu c_fpu;		/* external FPU state */
	int	c_ucode;		/* Exception no. from u_code */
};

The members of the structure are:

c_magic

The magic number CORE_MAGIC , as defined in <sys/core.h>.

c_len

The length of the core structure in the core file. This need not be equal to the current size of a core structure as defined in <sys/core.h>, as the core file may have been produced on a different release of the SunOS operating system.

c_regs

The general purpose registers at the time the core file was produced. This structure is machine-dependent.

c_aouthdr

The executable image header of the program.

c_signo

The number of the signal that terminated the process; see sigvec.2

c_tsize

The size of the text segment of the process at the time the core file was produced.

c_dsize

The size of the data segment of the process at the time the core file was produced. This gives the amount of data space image in the core file.

c_ssize

The size of the stack segment of the process at the time the core file was produced. This gives the amount of stack space image in the core file.

c_cmdname

The first CORE_NAMELEN characters of the last component of the path name of the program.

c_fpu

The status of the floating point hardware at the time the core file was produced.

c_ucode

The signal code of the signal that terminated the process, if any. See sigvec.2

SEE ALSO

Created by unroff & hp-tools. © somebody (See intro for details). All Rights Reserved. Last modified 11/5/97