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libdmmp.h(3) Library Functions Manual 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():%d0, _DMMP_LOG_STRERR_ALIGN_WIDTH - printed_bytes, "", file, func_name, line); } else { fprintf(stderr, " # %s:%s():%d0, 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 %s0, 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@redhat.com>
January 2016 Device Mapper Multipath API - libdmmp Manual