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diff --git a/devdocs/gnu_make/loaded-object-example.html b/devdocs/gnu_make/loaded-object-example.html new file mode 100644 index 00000000..bc4ca849 --- /dev/null +++ b/devdocs/gnu_make/loaded-object-example.html @@ -0,0 +1,67 @@ + <h1 class="subsection">Example Loaded Object</h1> <p>Let’s suppose we wanted to write a new GNU <code>make</code> function that would create a temporary file and return its name. We would like our function to take a prefix as an argument. First we can write the function in a file <samp>mk_temp.c</samp>: </p> <div class="example"> <pre class="example">#include <stdlib.h> +#include <stdio.h> +#include <string.h> +#include <unistd.h> +#include <errno.h> + +#include <gnumake.h> + +int plugin_is_GPL_compatible; + +char * +gen_tmpfile(const char *nm, int argc, char **argv) +{ + int fd; + + /* Compute the size of the filename and allocate space for it. */ + int len = strlen (argv[0]) + 6 + 1; + char *buf = gmk_alloc (len); + + strcpy (buf, argv[0]); + strcat (buf, "XXXXXX"); + + fd = mkstemp(buf); + if (fd >= 0) + { + /* Don't leak the file descriptor. */ + close (fd); + return buf; + } + + /* Failure. */ + fprintf (stderr, "mkstemp(%s) failed: %s\n", buf, strerror (errno)); + gmk_free (buf); + return NULL; +} + +int +mk_temp_gmk_setup (const gmk_floc *floc) +{ + printf ("mk_temp plugin loaded from %s:%lu\n", floc->filenm, floc->lineno); + /* Register the function with make name "mk-temp". */ + gmk_add_function ("mk-temp", gen_tmpfile, 1, 1, 1); + return 1; +} +</pre> +</div> <p>Next, we will write a <samp>Makefile</samp> that can build this shared object, load it, and use it: </p> <div class="example"> <pre class="example">all: + @echo Temporary file: $(mk-temp tmpfile.) + +load mk_temp.so + +mk_temp.so: mk_temp.c + $(CC) -shared -fPIC -o $@ $< +</pre> +</div> <p>On MS-Windows, due to peculiarities of how shared objects are produced, the compiler needs to scan the <em>import library</em> produced when building <code>make</code>, typically called <samp>libgnumake-<var>version</var>.dll.a</samp>, where <var>version</var> is the version of the load object API. So the recipe to produce a shared object will look on Windows like this (assuming the API version is 1): </p> <div class="example"> <pre class="example">mk_temp.dll: mk_temp.c + $(CC) -shared -o $@ $< -lgnumake-1 +</pre> +</div> <p>Now when you run <code>make</code> you’ll see something like: </p> <div class="example"> <pre class="example">$ make +mk_temp plugin loaded from Makefile:4 +cc -shared -fPIC -o mk_temp.so mk_temp.c +Temporary filename: tmpfile.A7JEwd +</pre> +</div><div class="_attribution"> + <p class="_attribution-p"> + Copyright © 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022 Free Software Foundation, Inc. <br>Licensed under the GNU Free Documentation License.<br> + <a href="https://www.gnu.org/software/make/manual/html_node/Loaded-Object-Example.html" class="_attribution-link">https://www.gnu.org/software/make/manual/html_node/Loaded-Object-Example.html</a> + </p> +</div> |