diff options
| author | Alejandro Colomar <alx.manpages@gmail.com> | 2022-09-05 23:03:38 +0200 |
|---|---|---|
| committer | Alejandro Colomar <alx.manpages@gmail.com> | 2022-09-05 23:03:47 +0200 |
| commit | 70ac1c4785fc1e158ab2349a962dba2526bf4fbc (patch) | |
| tree | bff270e2496dd284bccfc1271b43946f5d225224 /man/man3/end.3 | |
| parent | 5423a6f86b2b920a5f3e8cf8d759b513050f2d33 (diff) | |
| download | man-pages-70ac1c4785fc1e158ab2349a962dba2526bf4fbc.tar.gz | |
src.mk, All pages: Move man* to man/
The root of the repository is becoming a bit overpopulated and
unorganized, due to the recent addition of more mandirs, and more
informative and configuration files too. Let's create a specific
mandir <man/> that contains the mandirs <man[1-8]*>.
Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
Diffstat (limited to 'man/man3/end.3')
| -rw-r--r-- | man/man3/end.3 | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/man/man3/end.3 b/man/man3/end.3 new file mode 100644 index 0000000000..ca9a5be117 --- /dev/null +++ b/man/man3/end.3 @@ -0,0 +1,92 @@ +.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH END 3 2020-06-09 "Linux man-pages (unreleased)" +.SH NAME +etext, edata, end \- end of program segments +.SH SYNOPSIS +.nf +.BI extern " etext" ; +.BI extern " edata" ; +.BI extern " end" ; +.fi +.SH DESCRIPTION +The addresses of these symbols indicate the end of various program +segments: +.TP +.I etext +This is the first address past the end of the text segment +(the program code). +.TP +.I edata +This is the first address past the end of the +initialized data segment. +.TP +.I end +This is the first address past the end of the +uninitialized data segment (also known as the BSS segment). +.SH STANDARDS +Although these symbols have long been provided on most UNIX systems, +they are not standardized; use with caution. +.SH NOTES +The program must explicitly declare these symbols; +they are not defined in any header file. +.PP +On some systems the names of these symbols are preceded by underscores, +thus: +.IR _etext , +.IR _edata , +and +.IR _end . +These symbols are also defined for programs compiled on Linux. +.PP +At the start of program execution, +the program break will be somewhere near +.I &end +(perhaps at the start of the following page). +However, the break will change as memory is allocated via +.BR brk (2) +or +.BR malloc (3). +Use +.BR sbrk (2) +with an argument of zero to find the current value of the program break. +.SH EXAMPLES +When run, the program below produces output such as the following: +.PP +.in +4n +.EX +.RB "$" " ./a.out" +First address past: + program text (etext) 0x8048568 + initialized data (edata) 0x804a01c + uninitialized data (end) 0x804a024 +.EE +.in +.SS Program source +\& +.EX +#include <stdio.h> +#include <stdlib.h> + +extern char etext, edata, end; /* The symbols must have some type, + or "gcc \-Wall" complains */ + +int +main(int argc, char *argv[]) +{ + printf("First address past:\en"); + printf(" program text (etext) %10p\en", &etext); + printf(" initialized data (edata) %10p\en", &edata); + printf(" uninitialized data (end) %10p\en", &end); + + exit(EXIT_SUCCESS); +} +.EE +.SH SEE ALSO +.BR objdump (1), +.BR readelf (1), +.BR sbrk (2), +.BR elf (5) |