darwin.c

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/*
 * Dynamic loading support for Darwin
 *
 * If dlopen() is available (Darwin 10.3 and later), we just use it.
 * Otherwise we emulate it with the older, now deprecated, NSLinkModule API.
 *
 * src/backend/port/dynloader/darwin.c
 */
#include "postgres.h"

#ifdef HAVE_DLOPEN
#include <dlfcn.h>
#else
#include <mach-o/dyld.h>
#endif

#include "dynloader.h"


#ifdef HAVE_DLOPEN

void *
pg_dlopen(char *filename)
{
    return dlopen(filename, RTLD_NOW | RTLD_GLOBAL);
}

void
pg_dlclose(void *handle)
{
    dlclose(handle);
}

PGFunction
pg_dlsym(void *handle, char *funcname)
{
    /* Do not prepend an underscore: see dlopen(3) */
    return dlsym(handle, funcname);
}

char *
pg_dlerror(void)
{
    return dlerror();
}
#else                           /* !HAVE_DLOPEN */

/*
 * These routines were taken from the Apache source, but were made
 * available with a PostgreSQL-compatible license.  Kudos Wilfredo
 * Sánchez <[email protected]>.
 */

static NSObjectFileImageReturnCode cofiff_result = NSObjectFileImageFailure;

void *
pg_dlopen(char *filename)
{
    NSObjectFileImage image;

    cofiff_result = NSCreateObjectFileImageFromFile(filename, &image);
    if (cofiff_result != NSObjectFileImageSuccess)
        return NULL;
    return NSLinkModule(image, filename,
                        NSLINKMODULE_OPTION_BINDNOW |
                        NSLINKMODULE_OPTION_RETURN_ON_ERROR);
}

void
pg_dlclose(void *handle)
{
    NSUnLinkModule(handle, FALSE);
}

PGFunction
pg_dlsym(void *handle, char *funcname)
{
    NSSymbol symbol;
    char       *symname = (char *) malloc(strlen(funcname) + 2);

    sprintf(symname, "_%s", funcname);
    if (NSIsSymbolNameDefined(symname))
    {
        symbol = NSLookupAndBindSymbol(symname);

        free(symname);
        return (PGFunction) NSAddressOfSymbol(symbol);
    }
    else
    {
        free(symname);
        return NULL;
    }
}

char *
pg_dlerror(void)
{
    NSLinkEditErrors c;
    int         errorNumber;
    const char *fileName;
    const char *errorString = NULL;

    switch (cofiff_result)
    {
        case NSObjectFileImageSuccess:
            /* must have failed in NSLinkModule */
            NSLinkEditError(&c, &errorNumber, &fileName, &errorString);
            if (errorString == NULL || *errorString == '\0')
                errorString = "unknown link-edit failure";
            break;
        case NSObjectFileImageFailure:
            errorString = "failed to open object file";
            break;
        case NSObjectFileImageInappropriateFile:
            errorString = "inappropriate object file";
            break;
        case NSObjectFileImageArch:
            errorString = "object file is for wrong architecture";
            break;
        case NSObjectFileImageFormat:
            errorString = "object file has wrong format";
            break;
        case NSObjectFileImageAccess:
            errorString = "insufficient permissions for object file";
            break;
        default:
            errorString = "unknown failure to open object file";
            break;
    }

    return (char *) errorString;
}

#endif   /* HAVE_DLOPEN */