/*
 * Various trivial helper wrappers around standard functions
 */
#include "cache.h"
#include "config.h"

static void do_nothing(size_t size)
{
}

static void (*try_to_free_routine)(size_t size) = do_nothing;

static int memory_limit_check(size_t size, int gentle)
{
        static size_t limit = 0;
        if (!limit) {
                limit = git_env_ulong("GIT_ALLOC_LIMIT", 0);
                if (!limit)
                        limit = SIZE_MAX;
        }
        if (size > limit) {
                if (gentle) {
                        error("attempting to allocate %"PRIuMAX" over limit %"PRIuMAX,
                              (uintmax_t)size, (uintmax_t)limit);
                        return -1;
                } else
                        die("attempting to allocate %"PRIuMAX" over limit %"PRIuMAX,
                            (uintmax_t)size, (uintmax_t)limit);
        }
        return 0;
}

try_to_free_t set_try_to_free_routine(try_to_free_t routine)
{
        try_to_free_t old = try_to_free_routine;
        if (!routine)
                routine = do_nothing;
        try_to_free_routine = routine;
        return old;
}

char *xstrdup(const char *str)
{
        char *ret = strdup(str);
        if (!ret) {
                try_to_free_routine(strlen(str) + 1);
                ret = strdup(str);
                if (!ret)
                        die("Out of memory, strdup failed");
        }
        return ret;
}

static void *do_xmalloc(size_t size, int gentle)
{
        void *ret;

        if (memory_limit_check(size, gentle))
                return NULL;
        ret = malloc(size);
        if (!ret && !size)
                ret = malloc(1);
        if (!ret) {
                try_to_free_routine(size);
                ret = malloc(size);
                if (!ret && !size)
                        ret = malloc(1);
                if (!ret) {
                        if (!gentle)
                                die("Out of memory, malloc failed (tried to allocate %lu bytes)",
                                    (unsigned long)size);
                        else {
                                error("Out of memory, malloc failed (tried to allocate %lu bytes)",
                                      (unsigned long)size);
                                return NULL;
                        }
                }
        }
#ifdef XMALLOC_POISON
        memset(ret, 0xA5, size);
#endif
        return ret;
}

void *xmalloc(size_t size)
{
        return do_xmalloc(size, 0);
}

static void *do_xmallocz(size_t size, int gentle)
{
        void *ret;
        if (unsigned_add_overflows(size, 1)) {
                if (gentle) {
                        error("Data too large to fit into virtual memory space.");
                        return NULL;
                } else
                        die("Data too large to fit into virtual memory space.");
        }
        ret = do_xmalloc(size + 1, gentle);
        if (ret)
                ((char*)ret)[size] = 0;
        return ret;
}

void *xmallocz(size_t size)
{
        return do_xmallocz(size, 0);
}

void *xmallocz_gently(size_t size)
{
        return do_xmallocz(size, 1);
}

/*
 * xmemdupz() allocates (len + 1) bytes of memory, duplicates "len" bytes of
 * "data" to the allocated memory, zero terminates the allocated memory,
 * and returns a pointer to the allocated memory. If the allocation fails,
 * the program dies.
 */
void *xmemdupz(const void *data, size_t len)
{
        return memcpy(xmallocz(len), data, len);
}

char *xstrndup(const char *str, size_t len)
{
        char *p = memchr(str, '\0', len);
        return xmemdupz(str, p ? p - str : len);
}

void *xrealloc(void *ptr, size_t size)
{
        void *ret;

        memory_limit_check(size, 0);
        ret = realloc(ptr, size);
        if (!ret && !size)
                ret = realloc(ptr, 1);
        if (!ret) {
                try_to_free_routine(size);
                ret = realloc(ptr, size);
                if (!ret && !size)
                        ret = realloc(ptr, 1);
                if (!ret)
                        die("Out of memory, realloc failed");
        }
        return ret;
}

void *xcalloc(size_t nmemb, size_t size)
{
        void *ret;

        if (unsigned_mult_overflows(nmemb, size))
                die("data too large to fit into virtual memory space");

        memory_limit_check(size * nmemb, 0);
        ret = calloc(nmemb, size);
        if (!ret && (!nmemb || !size))
                ret = calloc(1, 1);
        if (!ret) {
                try_to_free_routine(nmemb * size);
                ret = calloc(nmemb, size);
                if (!ret && (!nmemb || !size))
                        ret = calloc(1, 1);
                if (!ret)
                        die("Out of memory, calloc failed");
        }
        return ret;
}

/*
 * Limit size of IO chunks, because huge chunks only cause pain.  OS X
 * 64-bit is buggy, returning EINVAL if len >= INT_MAX; and even in
 * the absence of bugs, large chunks can result in bad latencies when
 * you decide to kill the process.
 *
 * We pick 8 MiB as our default, but if the platform defines SSIZE_MAX
 * that is smaller than that, clip it to SSIZE_MAX, as a call to
 * read(2) or write(2) larger than that is allowed to fail.  As the last
 * resort, we allow a port to pass via CFLAGS e.g. "-DMAX_IO_SIZE=value"
 * to override this, if the definition of SSIZE_MAX given by the platform
 * is broken.
 */
#ifndef MAX_IO_SIZE
# define MAX_IO_SIZE_DEFAULT (8*1024*1024)
# if defined(SSIZE_MAX) && (SSIZE_MAX < MAX_IO_SIZE_DEFAULT)
#  define MAX_IO_SIZE SSIZE_MAX
# else
#  define MAX_IO_SIZE MAX_IO_SIZE_DEFAULT
# endif
#endif

/**
 * xopen() is the same as open(), but it die()s if the open() fails.
 */
int xopen(const char *path, int oflag, ...)
{
        mode_t mode = 0;
        va_list ap;

        /*
         * va_arg() will have undefined behavior if the specified type is not
         * compatible with the argument type. Since integers are promoted to
         * ints, we fetch the next argument as an int, and then cast it to a
         * mode_t to avoid undefined behavior.
         */
        va_start(ap, oflag);
        if (oflag & O_CREAT)
                mode = va_arg(ap, int);
        va_end(ap);

        for (;;) {
                int fd = open(path, oflag, mode);
                if (fd >= 0)
                        return fd;
                if (errno == EINTR)
                        continue;

                if ((oflag & O_RDWR) == O_RDWR)
                        die_errno(_("could not open '%s' for reading and writing"), path);
                else if ((oflag & O_WRONLY) == O_WRONLY)
                        die_errno(_("could not open '%s' for writing"), path);
                else
                        die_errno(_("could not open '%s' for reading"), path);
        }
}

static int handle_nonblock(int fd, short poll_events, int err)
{
        struct pollfd pfd;

        if (err != EAGAIN && err != EWOULDBLOCK)
                return 0;

        pfd.fd = fd;
        pfd.events = poll_events;

        /*
         * no need to check for errors, here;
         * a subsequent read/write will detect unrecoverable errors
         */
        poll(&pfd, 1, -1);
        return 1;
}

/*
 * xread() is the same a read(), but it automatically restarts read()
 * operations with a recoverable error (EAGAIN and EINTR). xread()
 * DOES NOT GUARANTEE that "len" bytes is read even if the data is available.
 */
ssize_t xread(int fd, void *buf, size_t len)
{
        ssize_t nr;
        if (len > MAX_IO_SIZE)
            len = MAX_IO_SIZE;
        while (1) {
                nr = read(fd, buf, len);
                if (nr < 0) {
                        if (errno == EINTR)
                                continue;
                        if (handle_nonblock(fd, POLLIN, errno))
                                continue;
                }
                return nr;
        }
}

/*
 * xwrite() is the same a write(), but it automatically restarts write()
 * operations with a recoverable error (EAGAIN and EINTR). xwrite() DOES NOT
 * GUARANTEE that "len" bytes is written even if the operation is successful.
 */
ssize_t xwrite(int fd, const void *buf, size_t len)
{
        ssize_t nr;
        if (len > MAX_IO_SIZE)
            len = MAX_IO_SIZE;
        while (1) {
                nr = write(fd, buf, len);
                if (nr < 0) {
                        if (errno == EINTR)
                                continue;
                        if (handle_nonblock(fd, POLLOUT, errno))
                                continue;
                }

                return nr;
        }
}

/*
 * xpread() is the same as pread(), but it automatically restarts pread()
 * operations with a recoverable error (EAGAIN and EINTR). xpread() DOES
 * NOT GUARANTEE that "len" bytes is read even if the data is available.
 */
ssize_t xpread(int fd, void *buf, size_t len, off_t offset)
{
        ssize_t nr;
        if (len > MAX_IO_SIZE)
                len = MAX_IO_SIZE;
        while (1) {
                nr = pread(fd, buf, len, offset);
                if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
                        continue;
                return nr;
        }
}

ssize_t read_in_full(int fd, void *buf, size_t count)
{
        char *p = buf;
        ssize_t total = 0;

        while (count > 0) {
                ssize_t loaded = xread(fd, p, count);
                if (loaded < 0)
                        return -1;
                if (loaded == 0)
                        return total;
                count -= loaded;
                p += loaded;
                total += loaded;
        }

        return total;
}

ssize_t write_in_full(int fd, const void *buf, size_t count)
{
        const char *p = buf;
        ssize_t total = 0;

        while (count > 0) {
                ssize_t written = xwrite(fd, p, count);
                if (written < 0)
                        return -1;
                if (!written) {
                        errno = ENOSPC;
                        return -1;
                }
                count -= written;
                p += written;
                total += written;
        }

        return total;
}

ssize_t pread_in_full(int fd, void *buf, size_t count, off_t offset)
{
        char *p = buf;
        ssize_t total = 0;

        while (count > 0) {
                ssize_t loaded = xpread(fd, p, count, offset);
                if (loaded < 0)
                        return -1;
                if (loaded == 0)
                        return total;
                count -= loaded;
                p += loaded;
                total += loaded;
                offset += loaded;
        }

        return total;
}

int xdup(int fd)
{
        int ret = dup(fd);
        if (ret < 0)
                die_errno("dup failed");
        return ret;
}

/**
 * xfopen() is the same as fopen(), but it die()s if the fopen() fails.
 */
FILE *xfopen(const char *path, const char *mode)
{
        for (;;) {
                FILE *fp = fopen(path, mode);
                if (fp)
                        return fp;
                if (errno == EINTR)
                        continue;

                if (*mode && mode[1] == '+')
                        die_errno(_("could not open '%s' for reading and writing"), path);
                else if (*mode == 'w' || *mode == 'a')
                        die_errno(_("could not open '%s' for writing"), path);
                else
                        die_errno(_("could not open '%s' for reading"), path);
        }
}

FILE *xfdopen(int fd, const char *mode)
{
        FILE *stream = fdopen(fd, mode);
        if (stream == NULL)
                die_errno("Out of memory? fdopen failed");
        return stream;
}

FILE *fopen_for_writing(const char *path)
{
        FILE *ret = fopen(path, "w");

        if (!ret && errno == EPERM) {
                if (!unlink(path))
                        ret = fopen(path, "w");
                else
                        errno = EPERM;
        }
        return ret;
}

static void warn_on_inaccessible(const char *path)
{
        warning_errno(_("unable to access '%s'"), path);
}

int warn_on_fopen_errors(const char *path)
{
        if (errno != ENOENT && errno != ENOTDIR) {
                warn_on_inaccessible(path);
                return -1;
        }

        return 0;
}

FILE *fopen_or_warn(const char *path, const char *mode)
{
        FILE *fp = fopen(path, mode);

        if (fp)
                return fp;

        warn_on_fopen_errors(path);
        return NULL;
}

int xmkstemp(char *filename_template)
{
        int fd;
        char origtemplate[PATH_MAX];
        strlcpy(origtemplate, filename_template, sizeof(origtemplate));

        fd = mkstemp(filename_template);
        if (fd < 0) {
                int saved_errno = errno;
                const char *nonrelative_template;

                if (strlen(filename_template) != strlen(origtemplate))
                        filename_template = origtemplate;

                nonrelative_template = absolute_path(filename_template);
                errno = saved_errno;
                die_errno("Unable to create temporary file '%s'",
                        nonrelative_template);
        }
        return fd;
}

/* Adapted from libiberty's mkstemp.c. */

#undef TMP_MAX
#define TMP_MAX 16384

int git_mkstemps_mode(char *pattern, int suffix_len, int mode)
{
        static const char letters[] =
                "abcdefghijklmnopqrstuvwxyz"
                "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
                "0123456789";
        static const int num_letters = 62;
        uint64_t value;
        struct timeval tv;
        char *filename_template;
        size_t len;
        int fd, count;

        len = strlen(pattern);

        if (len < 6 + suffix_len) {
                errno = EINVAL;
                return -1;
        }

        if (strncmp(&pattern[len - 6 - suffix_len], "XXXXXX", 6)) {
                errno = EINVAL;
                return -1;
        }

        /*
         * Replace pattern's XXXXXX characters with randomness.
         * Try TMP_MAX different filenames.
         */
        gettimeofday(&tv, NULL);
        value = ((size_t)(tv.tv_usec << 16)) ^ tv.tv_sec ^ getpid();
        filename_template = &pattern[len - 6 - suffix_len];
        for (count = 0; count < TMP_MAX; ++count) {
                uint64_t v = value;
                /* Fill in the random bits. */
                filename_template[0] = letters[v % num_letters]; v /= num_letters;
                filename_template[1] = letters[v % num_letters]; v /= num_letters;
                filename_template[2] = letters[v % num_letters]; v /= num_letters;
                filename_template[3] = letters[v % num_letters]; v /= num_letters;
                filename_template[4] = letters[v % num_letters]; v /= num_letters;
                filename_template[5] = letters[v % num_letters]; v /= num_letters;

                fd = open(pattern, O_CREAT | O_EXCL | O_RDWR, mode);
                if (fd >= 0)
                        return fd;
                /*
                 * Fatal error (EPERM, ENOSPC etc).
                 * It doesn't make sense to loop.
                 */
                if (errno != EEXIST)
                        break;
                /*
                 * This is a random value.  It is only necessary that
                 * the next TMP_MAX values generated by adding 7777 to
                 * VALUE are different with (module 2^32).
                 */
                value += 7777;
        }
        /* We return the null string if we can't find a unique file name.  */
        pattern[0] = '\0';
        return -1;
}

int git_mkstemp_mode(char *pattern, int mode)
{
        /* mkstemp is just mkstemps with no suffix */
        return git_mkstemps_mode(pattern, 0, mode);
}

int xmkstemp_mode(char *filename_template, int mode)
{
        int fd;
        char origtemplate[PATH_MAX];
        strlcpy(origtemplate, filename_template, sizeof(origtemplate));

        fd = git_mkstemp_mode(filename_template, mode);
        if (fd < 0) {
                int saved_errno = errno;
                const char *nonrelative_template;

                if (!filename_template[0])
                        filename_template = origtemplate;

                nonrelative_template = absolute_path(filename_template);
                errno = saved_errno;
                die_errno("Unable to create temporary file '%s'",
                        nonrelative_template);
        }
        return fd;
}

static int warn_if_unremovable(const char *op, const char *file, int rc)
{
        int err;
        if (!rc || errno == ENOENT)
                return 0;
        err = errno;
        warning_errno("unable to %s '%s'", op, file);
        errno = err;
        return rc;
}

int unlink_or_msg(const char *file, struct strbuf *err)
{
        int rc = unlink(file);

        assert(err);

        if (!rc || errno == ENOENT)
                return 0;

        strbuf_addf(err, "unable to unlink '%s': %s",
                    file, strerror(errno));
        return -1;
}

int unlink_or_warn(const char *file)
{
        return warn_if_unremovable("unlink", file, unlink(file));
}

int rmdir_or_warn(const char *file)
{
        return warn_if_unremovable("rmdir", file, rmdir(file));
}

int remove_or_warn(unsigned int mode, const char *file)
{
        return S_ISGITLINK(mode) ? rmdir_or_warn(file) : unlink_or_warn(file);
}

static int access_error_is_ok(int err, unsigned flag)
{
        return (is_missing_file_error(err) ||
                ((flag & ACCESS_EACCES_OK) && err == EACCES));
}

int access_or_warn(const char *path, int mode, unsigned flag)
{
        int ret = access(path, mode);
        if (ret && !access_error_is_ok(errno, flag))
                warn_on_inaccessible(path);
        return ret;
}

int access_or_die(const char *path, int mode, unsigned flag)
{
        int ret = access(path, mode);
        if (ret && !access_error_is_ok(errno, flag))
                die_errno(_("unable to access '%s'"), path);
        return ret;
}

char *xgetcwd(void)
{
        struct strbuf sb = STRBUF_INIT;
        if (strbuf_getcwd(&sb))
                die_errno(_("unable to get current working directory"));
        return strbuf_detach(&sb, NULL);
}

int xsnprintf(char *dst, size_t max, const char *fmt, ...)
{
        va_list ap;
        int len;

        va_start(ap, fmt);
        len = vsnprintf(dst, max, fmt, ap);
        va_end(ap);

        if (len < 0)
                BUG("your snprintf is broken");
        if (len >= max)
                BUG("attempt to snprintf into too-small buffer");
        return len;
}

void write_file_buf(const char *path, const char *buf, size_t len)
{
        int fd = xopen(path, O_WRONLY | O_CREAT | O_TRUNC, 0666);
        if (write_in_full(fd, buf, len) < 0)
                die_errno(_("could not write to '%s'"), path);
        if (close(fd))
                die_errno(_("could not close '%s'"), path);
}

void write_file(const char *path, const char *fmt, ...)
{
        va_list params;
        struct strbuf sb = STRBUF_INIT;

        va_start(params, fmt);
        strbuf_vaddf(&sb, fmt, params);
        va_end(params);

        strbuf_complete_line(&sb);

        write_file_buf(path, sb.buf, sb.len);
        strbuf_release(&sb);
}

void sleep_millisec(int millisec)
{
        poll(NULL, 0, millisec);
}

int xgethostname(char *buf, size_t len)
{
        /*
         * If the full hostname doesn't fit in buf, POSIX does not
         * specify whether the buffer will be null-terminated, so to
         * be safe, do it ourselves.
         */
        int ret = gethostname(buf, len);
        if (!ret)
                buf[len - 1] = 0;
        return ret;
}

int is_empty_or_missing_file(const char *filename)
{
        struct stat st;

        if (stat(filename, &st) < 0) {
                if (errno == ENOENT)
                        return 1;
                die_errno(_("could not stat %s"), filename);
        }

        return !st.st_size;
}