diff options
Diffstat (limited to 'ld/ld.texinfo')
| -rw-r--r-- | ld/ld.texinfo | 40 |
1 files changed, 37 insertions, 3 deletions
diff --git a/ld/ld.texinfo b/ld/ld.texinfo index 23fc78a..11d6d39 100644 --- a/ld/ld.texinfo +++ b/ld/ld.texinfo @@ -184,12 +184,12 @@ ld [ -o @var{output} ] @var{objfile}@dots{} [ -Ttext @var{org} ] [ -Tdata @var{org} ] [ -Tbss @var{org} ] [ -t ] [ -traditional-format ] [ -u @var{symbol}] [-V] [-v] [ -verbose] [ -version ] - [ -warn-common ] [ -warn-constructors] [ -warn-multiple-gp ] [ -warn-once ] - [ -y @var{symbol} ] [ -X ] [-x ] + [ -warn-common ] [ -warn-constructors] [ -warn-multiple-gp ] + [ -warn-once ] [ -y @var{symbol} ] [ -X ] [-x ] [ -( [ archives ] -) ] [ --start-group [ archives ] --end-group ] [ -split-by-reloc @var{count} ] [ -split-by-file ] - [ --whole-archive ] [ --no-whole-archive ] + [ --whole-archive ] [ --no-whole-archive ] [ --wrap @var{symbol} ] @end smallexample This plethora of command-line options may seem intimidating, but in @@ -968,6 +968,40 @@ library. Turn off the effect of the @code{--whole-archive} option for archives which appear later on the command line. +@kindex --wrap +@item --wrap @var{symbol} +Use a wrapper function for @var{symbol}. Any undefined reference to +@var{symbol} will be resolved to @code{__wrap_@var{symbol}}. Any +undefined reference to @code{__real_@var{symbol}} will be resolved to +@var{symbol}. + +This can be used to provide a wrapper for a system function. The +wrapper function should be called @code{__wrap_@var{symbol}}. If it +wishes to call the system function, it should call +@code{__real_@var{symbol}}. + +Here is a trivial example: + +@smallexample +void * +__wrap_malloc (int c) +@{ + printf ("malloc called with %ld\n", c); + return __real_malloc (c); +@} +@end smallexample + +If you link other code with this file using @code{--wrap malloc}, then +all calls to @code{malloc} will call the function @code{__wrap_malloc} +instead. The call to @code{__real_malloc} in @code{__wrap_malloc} will +call the real @code{malloc} function. + +You may wish to provide a @code{__real_malloc} function as well, so that +links without the @code{--wrap} option will succeed. If you do this, +you should not put the definition of @code{__real_malloc} in the same +file as @code{__wrap_malloc}; if you do, the assembler may resolve the +call before the linker has a chance to wrap it to @code{malloc}. + @kindex -X @cindex local symbols, deleting @cindex L, deleting symbols beginning |