]> git.ozlabs.org Git - ccan/blobdiff - ccan/talloc/_info
Rename _info.c to _info: this means we can simple compile *.c.
[ccan] / ccan / talloc / _info
diff --git a/ccan/talloc/_info b/ccan/talloc/_info
new file mode 100644 (file)
index 0000000..95c9153
--- /dev/null
@@ -0,0 +1,105 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * talloc - tree allocator routines
+ *
+ * Talloc is a hierarchical memory pool system with destructors: you keep your
+ * objects in heirarchies reflecting their lifetime.  Every pointer returned
+ * from talloc() is itself a valid talloc context, from which other talloc()s
+ * can be attached.  This means you can do this:
+ *
+ *  struct foo *X = talloc(mem_ctx, struct foo);
+ *  X->name = talloc_strdup(X, "foo");
+ *
+ * and the pointer X->name would be a "child" of the talloc context "X" which
+ * is itself a child of mem_ctx.  So if you do talloc_free(mem_ctx) then it is
+ * all destroyed, whereas if you do talloc_free(X) then just X and X->name are
+ * destroyed, and if you do talloc_free(X->name) then just the name element of
+ * X is destroyed.
+ *
+ * If you think about this, then what this effectively gives you is an n-ary
+ * tree, where you can free any part of the tree with talloc_free().
+ *
+ * Talloc has been measured with a time overhead of around 4% over glibc
+ * malloc, and 48/80 bytes per allocation (32/64 bit).
+ *
+ * This version is based on svn://svnanon.samba.org/samba/branches/SAMBA_4_0/source/lib/talloc revision 23158.
+ *
+ * Example:
+ *     #include <stdio.h>
+ *     #include <stdarg.h>
+ *     #include <err.h>
+ *     #include <ccan/talloc/talloc.h>
+ *
+ *     // A structure containing a popened command.
+ *     struct command
+ *     {
+ *             FILE *f;
+ *             const char *command;
+ *     };
+ *
+ *     // When struct command is freed, we also want to pclose pipe.
+ *     static int close_cmd(struct command *cmd)
+ *     {
+ *             pclose(cmd->f);
+ *             // 0 means "we succeeded, continue freeing"
+ *             return 0;
+ *     }
+ *
+ *     // This function opens a writable pipe to the given command.
+ *     struct command *open_output_cmd(const void *ctx, char *fmt, ...)
+ *     {
+ *             va_list ap;
+ *             struct command *cmd = talloc(ctx, struct command);
+ *
+ *             if (!cmd)
+ *                     return NULL;
+ *
+ *             va_start(ap, fmt);
+ *             cmd->command = talloc_vasprintf(cmd, fmt, ap);
+ *             va_end(ap);
+ *             if (!cmd->command) {
+ *                     talloc_free(cmd);
+ *                     return NULL;
+ *             }
+ *
+ *             cmd->f = popen(cmd->command, "w");
+ *             if (!cmd->f) {
+ *                     talloc_free(cmd);
+ *                     return NULL;
+ *             }
+ *             talloc_set_destructor(cmd, close_cmd);
+ *             return cmd;
+ *     }
+ *
+ *     int main(int argc, char *argv[])
+ *     {
+ *             struct command *cmd;
+ *
+ *             if (argc != 2)
+ *                     errx(1, "Usage: %s <command>\n", argv[0]);
+ *
+ *             cmd = open_output_cmd(NULL, "%s hello", argv[1]);
+ *             if (!cmd)
+ *                     err(1, "Running '%s hello'", argv[1]);
+ *             fprintf(cmd->f, "This is a test\n");
+ *             talloc_free(cmd);
+ *             return 0;
+ *     }
+ *
+ * Licence: GPL (2 or any later version)
+ */
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               return 1;
+
+       if (strcmp(argv[1], "depends") == 0) {
+               printf("ccan/typesafe_cb\n");
+               return 0;
+       }
+
+       return 1;
+}