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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:40:15 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-15 19:40:15 +0000 |
commit | 399644e47874bff147afb19c89228901ac39340e (patch) | |
tree | 1c4c0b733f4c16b5783b41bebb19194a9ef62ad1 /man3/end.3 | |
parent | Initial commit. (diff) | |
download | manpages-399644e47874bff147afb19c89228901ac39340e.tar.xz manpages-399644e47874bff147afb19c89228901ac39340e.zip |
Adding upstream version 6.05.01.upstream/6.05.01
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'man3/end.3')
-rw-r--r-- | man3/end.3 | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/man3/end.3 b/man3/end.3 new file mode 100644 index 0000000..a0691d6 --- /dev/null +++ b/man3/end.3 @@ -0,0 +1,96 @@ +.\" Copyright (c) 2008, Linux Foundation, written by Michael Kerrisk +.\" <mtk.manpages@gmail.com> +.\" +.\" SPDX-License-Identifier: Linux-man-pages-copyleft +.\" +.TH end 3 2023-05-03 "Linux man-pages 6.05.01" +.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 +None. +.SH HISTORY +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 +\& +.\" SRC BEGIN (end.c) +.EX +#include <stdio.h> +#include <stdlib.h> +\& +extern char etext, edata, end; /* The symbols must have some type, + or "gcc \-Wall" complains */ +\& +int +main(void) +{ + 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 +.\" SRC END +.SH SEE ALSO +.BR objdump (1), +.BR readelf (1), +.BR sbrk (2), +.BR elf (5) |