libdmmp.h(3)

NAME
libdmmp.h - Device Mapper Multipath API.

SYNOPSIS
#include <libdmmp/libdmmp.h>

DESCRIPTION

All the libdmmp public functions ships its own man pages. Use 'man 3 <function_name>' to check the detail usage.

USAGE

To use libdmmp in your project, we suggest to use the 'pkg-config' way:

 * Add this line into your configure.ac:

    PKG_CHECK_MODULES([LIBDMMP], [libdmmp])

 * Add these lines into your Makefile.am:

    foo_LDFLAGS += $(LIBDMMP_LIBS)
    foo_CFLAGS += $(LIBDMMP_CFLAGS)

LOG HANDLING

The log handler function could be set via 'dmmp_context_log_func_set()'. The log priority could be set via 'dmmp_context_log_priority_set()'.

By default, the log priorities is 'DMMP_LOG_PRIORITY_WARNING'. By default, the log handler is print log to STDERR, and its code is listed below in case you want to create your own log handler.

        static int _DMMP_LOG_STRERR_ALIGN_WIDTH = 80;

        static void _log_stderr(struct dmmp_context *ctx,
                        enum dmmp_log_priority priority,
                        const char *file, int line,
                        const char *func_name,
                        const char *format, va_list args)
        {
            int printed_bytes = 0;

            printed_bytes += fprintf(stderr, "libdmmp %s: ",
                        dmmp_log_priority_str(priority));
            printed_bytes += vfprintf(stderr, format, args);
            userdata = dmmp_context_userdata_get(ctx);
            if (userdata != NULL)
                fprintf(stderr, "(with user data at memory address %p)",
                        userdata);

            if (printed_bytes < _DMMP_LOG_STRERR_ALIGN_WIDTH) {
                fprintf(stderr, "%*s # %s:%s():%d,
                        _DMMP_LOG_STRERR_ALIGN_WIDTH - printed_bytes, "", file,
                        func_name, line);
            } else {
                fprintf(stderr, " # %s:%s():%d, file, func_name, line);
            }
        }

SAMPLE CODE

    #include <libdmmp/libdmmp.h>

    int main(int argc, char *argv[]) {
        struct dmmp_context *ctx = NULL;
        struct dmmp_mpath **dmmp_mps = NULL;
        struct dmmp_path_group **dmmp_pgs = NULL;
        struct dmmp_path **dmmp_ps = NULL;
        uint32_t dmmp_mp_count = 0;
        uint32_t dmmp_pg_count = 0;
        uint32_t dmmp_p_count = 0;
        const char *name = NULL;
        const char *wwid = NULL;
        uint32_t i = 0;
        int rc = DMMP_OK;

        ctx = dmmp_context_new();
        dmmp_context_log_priority_set(ctx, DMMP_LOG_PRIORITY_DEBUG);
        // By default, log will be printed to STDERR, you could
        // change that via dmmp_context_log_func_set()
        rc = dmmp_mpath_array_get(ctx, &dmmp_mps, &dmmp_mp_count);
        if (rc != DMMP_OK) {
            printf("dmmp_mpath_array_get() failed with %d: %s", rc,
                   dmmp_strerror(rc));
            goto out;
        }
        for (i = 0; i < dmmp_mp_count; ++i) {
                name = dmmp_mpath_name_get(dmmp_mps[i]);
                wwid = dmmp_mpath_wwid_get(dmmp_mps[i]);
                printf("dmmp_mpath_array_get(): Got mpath: %s %s, name,
                       wwid);
                // You could use dmmp_path_group_array_get() to retrieve
                // path group information and then invoke dmmp_path_array_get()
                // for path information.
        }

     out:
        dmmp_context_free(ctx);
        dmmp_mpath_array_free(dmmp_mps, dmmp_mp_count);
        if (rc != DMMP_OK)
            exit(1);
        exit(0);
    }

LICENSE
GPLv2+

BUG
Please report bug to <dm-devel@lists.linux.dev>