GNU Info

(gawk.info)Using Internal File Ops

---

Prev: Internal File Ops Up: Sample Library

---

Enter node , (file) or (file)node

Integrating the Extensions
..........................

   Now that the code is written, it must be possible to add it at
runtime to the running `gawk' interpreter.  First, the code must be
compiled.  Assuming that the functions are in a file named
`filefuncs.c', and IDIR is the location of the `gawk' include files,
the following steps create a GNU/Linux shared library:

     $ gcc -shared -DHAVE_CONFIG_H -c -O -g -IIDIR filefuncs.c
     $ ld -o filefuncs.so -shared filefuncs.o

   Once the library exists, it is loaded by calling the `extension'
built-in function.  This function takes two arguments: the name of the
library to load and the name of a function to call when the library is
first loaded. This function adds the new functions to `gawk'.  It
returns the value returned by the initialization function within the
shared library:

     # file testff.awk
     BEGIN {
         extension("./filefuncs.so", "dlload")
     
         chdir(".")  # no-op
     
         data[1] = 1 # force `data' to be an array
         print "Info for testff.awk"
         ret = stat("testff.awk", data)
         print "ret =", ret
         for (i in data)
             printf "data[\"%s\"] = %s\n", i, data[i]
         print "testff.awk modified:",
             strftime("%m %d %y %H:%M:%S", data["mtime"])
     }

   Here are the results of running the program:

     $ gawk -f testff.awk
     -| Info for testff.awk
     -| ret = 0
     -| data["blksize"] = 4096
     -| data["mtime"] = 932361936
     -| data["mode"] = 33188
     -| data["type"] = file
     -| data["dev"] = 2065
     -| data["gid"] = 10
     -| data["ino"] = 878597
     -| data["ctime"] = 971431797
     -| data["blocks"] = 2
     -| data["nlink"] = 1
     -| data["name"] = testff.awk
     -| data["atime"] = 971608519
     -| data["pmode"] = -rw-r--r--
     -| data["size"] = 607
     -| data["uid"] = 2076
     -| testff.awk modified: 07 19 99 08:25:36