This is a more portable variant of the ELF section trick.
--- /dev/null
+../../licenses/BSD-MIT
\ No newline at end of file
--- /dev/null
+#include <string.h>
+#include "config.h"
+
+/**
+ * autodata - stash pointers in your binary for automatic registration
+ *
+ * This code allows declarations in your source which you can gather
+ * together at runtime to form tables. This is often used in place of
+ * having to patch a registration function call out, or a central
+ * table.
+ *
+ * License: BSD-MIT
+ */
+int main(int argc, char *argv[])
+{
+ /* Expect exactly one argument */
+ if (argc != 2)
+ return 1;
+
+ if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/compiler\n");
+ printf("ccan/ptr_valid\n");
+ return 0;
+ }
+
+ return 1;
+}
--- /dev/null
+// Licensed under BSD-MIT: See LICENSE.
+#include "autodata.h"
+#include <stdint.h>
+#include <unistd.h>
+#include <string.h>
+
+#if HAVE_SECTION_START_STOP
+void *autodata_get_section(void *start, void *stop, size_t *nump)
+{
+ *nump = (void **)(stop) - (void **)(start);
+ return start;
+}
+
+void autodata_free(void *table)
+{
+}
+#else
+#include <ccan/ptr_valid/ptr_valid.h>
+
+void *autodata_make_table(const void *example, const char *name, size_t *nump)
+{
+ const char *start, *end, *tag;
+ struct ptr_valid_batch batch;
+ const void *const magic = (void *)AUTODATA_MAGIC;
+ void **table = NULL;
+ char first_magic;
+
+ if (!ptr_valid_batch_start(&batch))
+ return NULL;
+
+ /* Get range to search. */
+ for (start = (char *)((intptr_t)example & ~(getpagesize() - 1));
+ ptr_valid_batch(&batch, start-getpagesize(), 1, sizeof(void *),
+ false);
+ start -= getpagesize());
+
+ for (end = (char *)((intptr_t)example & ~(getpagesize() - 1));
+ ptr_valid_batch(&batch, end, 1, sizeof(void *), false);
+ end += getpagesize());
+
+ *nump = 0;
+ first_magic = *(char *)&magic;
+ for (tag = memchr(start, first_magic, end - start);
+ tag;
+ tag = memchr(tag+1, first_magic, end - (tag + 1))) {
+ void *adata[4];
+
+ /* We can read 4 void *'s here? */
+ if (tag + sizeof(adata) > end)
+ continue;
+
+ memcpy(adata, tag, sizeof(adata));
+
+ /* False match? */
+ if (adata[0] != (void *)AUTODATA_MAGIC || adata[1] != tag)
+ continue;
+
+ /* OK, check name. */
+ if (!ptr_valid_batch_string(&batch, adata[3])
+ || strcmp(name, adata[3]) != 0)
+ continue;
+
+ if (!ptr_valid_batch_read(&batch, (char *)adata[2]))
+ continue;
+
+ table = realloc(table, sizeof(void *) * (*nump + 1));
+ if (!table)
+ break;
+ table[*nump] = adata[2];
+ (*nump)++;
+ }
+ ptr_valid_batch_end(&batch);
+ return table;
+}
+
+void autodata_free(void *table)
+{
+ free(table);
+}
+#endif
--- /dev/null
+// Licensed under BSD-MIT: See LICENSE.
+#ifndef CCAN_AUTODATA_H
+#define CCAN_AUTODATA_H
+#include "config.h"
+#include <ccan/compiler/compiler.h>
+#include <stdlib.h>
+
+#if HAVE_SECTION_START_STOP
+
+/**
+ * AUTODATA_TYPE - declare the type for a given autodata name.
+ * @name: the name for this set of autodata
+ * @type: the type this autodata points to
+ *
+ * This macro is usually placed in a header: it must preceed any
+ * autodata functions in the file.
+ *
+ * Example:
+ * // My set of char pointers.
+ * AUTODATA_TYPE(names, char);
+ */
+#define AUTODATA_TYPE(name, type) \
+ typedef type autodata_##name##_; \
+ extern type *__start_autodata_##name[], *__stop_autodata_##name[]
+
+/**
+ * AUTODATA - add a pointer to this autodata set
+ * @name: the name of the set of autodata
+ * @ptr: the compile-time-known pointer
+ *
+ * This embeds @ptr into the binary, with the tag corresponding to
+ * @name (which must look like a valid identifier, no punctuation!).
+ * The type of @ptr must match that given by AUTODATA_TYPE. It is
+ * usually a file-level declaration.
+ *
+ * Example:
+ * // Put two char pointers into the names AUTODATA set.
+ * AUTODATA(names, "Arabella");
+ * AUTODATA(names, "Alex");
+ */
+#define AUTODATA(name, ptr) \
+ static const autodata_##name##_ *NEEDED \
+ __attribute__((section("autodata_" #name))) \
+ AUTODATA_VAR_(name, __LINE__) = (ptr);
+
+/**
+ * autodata_get - get an autodata set
+ * @name: the name of the set of autodata
+ * @nump: the number of items in the set.
+ *
+ * This extract the embedded pointers matching @name. It may fail
+ * if malloc() fails, or if there is no AUTODATA at all.
+ *
+ * The return will be a pointer to an array of @type pointers (from
+ * AUTODATA_TYPE).
+ *
+ * Example:
+ * static void print_embedded_names(void)
+ * {
+ * unsigned int i, num;
+ * char **n = autodata_get(names, &num);
+ *
+ * for (i = 0; i < num; i++)
+ * printf("%s\n", n[i]);
+ * }
+ */
+#define autodata_get(name, nump) \
+ ((autodata_##name##_ **) \
+ autodata_get_section(__start_autodata_##name, \
+ __stop_autodata_##name, (nump)))
+#endif /* HAVE_SECTION_START_STOP */
+
+/**
+ * autodata_free - free the table returned by autodata_get()
+ * @p: the table.
+ */
+void autodata_free(void *p);
+
+/* Internal functions. */
+#define AUTODATA_VAR__(name, line) autodata_##name##_##line
+#define AUTODATA_VAR_(name, line) AUTODATA_VAR__(name, line)
+
+#if HAVE_SECTION_START_STOP
+void *autodata_get_section(void *start, void *stop, size_t *nump);
+#else
+#define AUTODATA_TYPE(name, type) \
+ typedef type autodata_##name##_; \
+ static const void *autodata_##name##_ex = &autodata_##name##_ex
+
+#define AUTODATA_MAGIC ((long)0xFEEDA10DA7AF00D5ULL)
+#define AUTODATA(name, ptr) \
+ static const autodata_##name##_ *NEEDED \
+ AUTODATA_VAR_(name, __LINE__)[4] = \
+ { (void *)AUTODATA_MAGIC, \
+ (void *)&AUTODATA_VAR_(name, __LINE__), \
+ (ptr), \
+ (void *)#name }
+
+#define autodata_get(name, nump) \
+ ((autodata_##name##_ **) \
+ autodata_make_table(&autodata_##name##_ex, #name, (nump)))
+
+void *autodata_make_table(const void *example, const char *name, size_t *nump);
+#endif
+
+#endif /* CCAN_AUTODATA_H */
--- /dev/null
+/* Check that linking together works. */
+#include <ccan/autodata/autodata.h>
+
+AUTODATA_TYPE(autostrings, char);
+
+AUTODATA(autostrings, "helper");
--- /dev/null
+#include <ccan/autodata/autodata.h>
+/* Include the C files directly. */
+#include <ccan/autodata/autodata.c>
+#include <ccan/tap/tap.h>
+
+AUTODATA_TYPE(autostrings, char);
+
+AUTODATA(autostrings, "genuine");
+
+#if !HAVE_SECTION_START_STOP
+/* These are all fake, to test the various failure paths. */
+/* Hopefully fake_alpha or fake_omega will test run-past-end. */
+static const void *NEEDED fake_alpha[] = { (void *)AUTODATA_MAGIC };
+
+/* Wrong magic in the middle. */
+static const void *NEEDED fake1[] = { (void *)(AUTODATA_MAGIC ^ 0x10000),
+ (void *)&fake1,
+ "fake1",
+ (void *)"autostrings" };
+
+/* Wrong self pointer. */
+static const void *NEEDED fake2[] = { (void *)AUTODATA_MAGIC,
+ (void *)&fake1,
+ "fake2",
+ (void *)"autostrings" };
+
+/* Wrong name. */
+static const void *NEEDED fake3[] = { (void *)AUTODATA_MAGIC,
+ (void *)&fake3,
+ "fake3",
+ (void *)"autostrings2" };
+
+/* Invalid self-pointer. */
+static const void *NEEDED fake4[] = { (void *)AUTODATA_MAGIC,
+ (void *)1UL,
+ "fake4",
+ (void *)"autostrings" };
+
+/* Invalid name pointer */
+static const void *NEEDED fake5[] = { (void *)AUTODATA_MAGIC,
+ (void *)&fake5,
+ "fake5",
+ (void *)1UL };
+
+/* Invalid contents pointer */
+static const void *NEEDED fake6[] = { (void *)AUTODATA_MAGIC,
+ (void *)&fake6,
+ (char *)1UL,
+ (void *)"autostrings" };
+
+static const void *NEEDED fake_omega[] = { (void *)AUTODATA_MAGIC };
+#endif
+
+int main(void)
+{
+ char **table;
+ size_t num;
+
+ /* This is how many tests you plan to run */
+ plan_tests(2);
+
+ table = autodata_get(autostrings, &num);
+ ok1(num == 2);
+ ok1((!strcmp(table[0], "genuine") && !strcmp(table[1], "helper"))
+ || (!strcmp(table[1], "genuine") && !strcmp(table[0], "helper")));
+
+ autodata_free(table);
+
+ /* This exits depending on whether all tests passed */
+ return exit_status();
+}
--- /dev/null
+#include <ccan/autodata/autodata.h>
+/* Include the C files directly. */
+#include <ccan/autodata/autodata.c>
+#include <ccan/tap/tap.h>
+
+AUTODATA_TYPE(autostrings, char);
+
+AUTODATA(autostrings, "hello");
+AUTODATA(autostrings, "world");
+
+int main(void)
+{
+ char **table;
+ size_t num;
+ int i, hello = -1, world = -1, helper = -1;
+
+ /* This is how many tests you plan to run */
+ plan_tests(4);
+
+ table = autodata_get(autostrings, &num);
+ ok1(num == 3);
+
+ for (i = 0; i < num; i++) {
+ if (strcmp(table[i], "hello") == 0)
+ hello = i;
+ else if (strcmp(table[i], "world") == 0)
+ world = i;
+ else if (strcmp(table[i], "helper") == 0)
+ helper = i;
+ else
+ fail("Unknown entry %s", table[i]);
+ }
+ ok1(hello != -1);
+ ok1(world != -1);
+ ok1(helper != -1);
+
+ autodata_free(table);
+
+ /* This exits depending on whether all tests passed */
+ return exit_status();
+}
projects / ccan / commitdiff