Introduce (private) ZLibFilter to dart:io.

runtime/third_party/zlib/gzlib.c

+/* gzlib.c -- zlib functions common to reading and writing gzip files
+ * Copyright (C) 2004, 2010, 2011, 2012 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include "gzguts.h"
+
+#if defined(_WIN32) && !defined(__BORLANDC__)
+#  define LSEEK _lseeki64
+#else
+#if defined(_LARGEFILE64_SOURCE) && _LFS64_LARGEFILE-0
+#  define LSEEK lseek64
+#else
+#  define LSEEK lseek
+#endif
+#endif
+
+/* Local functions */
+local void gz_reset OF((gz_statep));
+local gzFile gz_open OF((const void *, int, const char *));
+
+#if defined UNDER_CE
+
+/* Map the Windows error number in ERROR to a locale-dependent error message
+   string and return a pointer to it.  Typically, the values for ERROR come
+   from GetLastError.
+
+   The string pointed to shall not be modified by the application, but may be
+   overwritten by a subsequent call to gz_strwinerror
+
+   The gz_strwinerror function does not change the current setting of
+   GetLastError. */
+char ZLIB_INTERNAL *gz_strwinerror (error)
+     DWORD error;
+{
+    static char buf[1024];
+
+    wchar_t *msgbuf;
+    DWORD lasterr = GetLastError();
+    DWORD chars = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM
+        | FORMAT_MESSAGE_ALLOCATE_BUFFER,
+        NULL,
+        error,
+        0, /* Default language */
+        (LPVOID)&msgbuf,
+        0,
+        NULL);
+    if (chars != 0) {
+        /* If there is an \r\n appended, zap it.  */
+        if (chars >= 2
+            && msgbuf[chars - 2] == '\r' && msgbuf[chars - 1] == '\n') {
+            chars -= 2;
+            msgbuf[chars] = 0;
+        }
+
+        if (chars > sizeof (buf) - 1) {
+            chars = sizeof (buf) - 1;
+            msgbuf[chars] = 0;
+        }
+
+        wcstombs(buf, msgbuf, chars + 1);
+        LocalFree(msgbuf);
+    }
+    else {
+        sprintf(buf, "unknown win32 error (%ld)", error);
+    }
+
+    SetLastError(lasterr);
+    return buf;
+}
+
+#endif /* UNDER_CE */
+
+/* Reset gzip file state */
+local void gz_reset(state)
+    gz_statep state;
+{
+    state->x.have = 0;              /* no output data available */
+    if (state->mode == GZ_READ) {   /* for reading ... */
+        state->eof = 0;             /* not at end of file */
+        state->past = 0;            /* have not read past end yet */
+        state->how = LOOK;          /* look for gzip header */
+    }
+    state->seek = 0;                /* no seek request pending */
+    gz_error(state, Z_OK, NULL);    /* clear error */
+    state->x.pos = 0;               /* no uncompressed data yet */
+    state->strm.avail_in = 0;       /* no input data yet */
+}
+
+/* Open a gzip file either by name or file descriptor. */
+local gzFile gz_open(path, fd, mode)
+    const void *path;
+    int fd;
+    const char *mode;
+{
+    gz_statep state;
+    size_t len;
+    int oflag;
+#ifdef O_CLOEXEC
+    int cloexec = 0;
+#endif
+#ifdef O_EXCL
+    int exclusive = 0;
+#endif
+
+    /* check input */
+    if (path == NULL)
+        return NULL;
+
+    /* allocate gzFile structure to return */
+    state = malloc(sizeof(gz_state));
+    if (state == NULL)
+        return NULL;
+    state->size = 0;            /* no buffers allocated yet */
+    state->want = GZBUFSIZE;    /* requested buffer size */
+    state->msg = NULL;          /* no error message yet */
+
+    /* interpret mode */
+    state->mode = GZ_NONE;
+    state->level = Z_DEFAULT_COMPRESSION;
+    state->strategy = Z_DEFAULT_STRATEGY;
+    state->direct = 0;
+    while (*mode) {
+        if (*mode >= '0' && *mode <= '9')
+            state->level = *mode - '0';
+        else
+            switch (*mode) {
+            case 'r':
+                state->mode = GZ_READ;
+                break;
+#ifndef NO_GZCOMPRESS
+            case 'w':
+                state->mode = GZ_WRITE;
+                break;
+            case 'a':
+                state->mode = GZ_APPEND;
+                break;
+#endif
+            case '+':       /* can't read and write at the same time */
+                free(state);
+                return NULL;
+            case 'b':       /* ignore -- will request binary anyway */
+                break;
+#ifdef O_CLOEXEC
+            case 'e':
+                cloexec = 1;
+                break;
+#endif
+#ifdef O_EXCL
+            case 'x':
+                exclusive = 1;
+                break;
+#endif
+            case 'f':
+                state->strategy = Z_FILTERED;
+                break;
+            case 'h':
+                state->strategy = Z_HUFFMAN_ONLY;
+                break;
+            case 'R':
+                state->strategy = Z_RLE;
+                break;
+            case 'F':
+                state->strategy = Z_FIXED;
+            case 'T':
+                state->direct = 1;
+            default:        /* could consider as an error, but just ignore */
+                ;
+            }
+        mode++;
+    }
+
+    /* must provide an "r", "w", or "a" */
+    if (state->mode == GZ_NONE) {
+        free(state);
+        return NULL;
+    }
+
+    /* can't force transparent read */
+    if (state->mode == GZ_READ) {
+        if (state->direct) {
+            free(state);
+            return NULL;
+        }
+        state->direct = 1;      /* for empty file */
+    }
+
+    /* save the path name for error messages */
+#ifdef _WIN32
+    if (fd == -2) {
+        len = wcstombs(NULL, path, 0);
+        if (len == (size_t)-1)
+            len = 0;
+    }
+    else
+#endif
+        len = strlen(path);
+    state->path = malloc(len + 1);
+    if (state->path == NULL) {
+        free(state);
+        return NULL;
+    }
+#ifdef _WIN32
+    if (fd == -2)
+        if (len)
+            wcstombs(state->path, path, len + 1);
+        else
+            *(state->path) = 0;
+    else
+#endif
+        strcpy(state->path, path);
+
+    /* compute the flags for open() */
+    oflag =
+#ifdef O_LARGEFILE
+        O_LARGEFILE |
+#endif
+#ifdef O_BINARY
+        O_BINARY |
+#endif
+#ifdef O_CLOEXEC
+        (cloexec ? O_CLOEXEC : 0) |
+#endif
+        (state->mode == GZ_READ ?
+         O_RDONLY :
+         (O_WRONLY | O_CREAT |
+#ifdef O_EXCL
+          (exclusive ? O_EXCL : 0) |
+#endif
+          (state->mode == GZ_WRITE ?
+           O_TRUNC :
+           O_APPEND)));
+
+    /* open the file with the appropriate flags (or just use fd) */
+    state->fd = fd > -1 ? fd : (
+#ifdef _WIN32
+        fd == -2 ? _wopen(path, oflag, 0666) :
+#endif
+        open(path, oflag, 0666));
+    if (state->fd == -1) {
+        free(state->path);
+        free(state);
+        return NULL;
+    }
+    if (state->mode == GZ_APPEND)
+        state->mode = GZ_WRITE;         /* simplify later checks */
+
+    /* save the current position for rewinding (only if reading) */
+    if (state->mode == GZ_READ) {
+        state->start = LSEEK(state->fd, 0, SEEK_CUR);
+        if (state->start == -1) state->start = 0;
+    }
+
+    /* initialize stream */
+    gz_reset(state);
+
+    /* return stream */
+    return (gzFile)state;
+}
+
+/* -- see zlib.h -- */
+gzFile ZEXPORT gzopen(path, mode)
+    const char *path;
+    const char *mode;
+{
+    return gz_open(path, -1, mode);
+}
+
+/* -- see zlib.h -- */
+gzFile ZEXPORT gzopen64(path, mode)
+    const char *path;
+    const char *mode;
+{
+    return gz_open(path, -1, mode);
+}
+
+/* -- see zlib.h -- */
+gzFile ZEXPORT gzdopen(fd, mode)
+    int fd;
+    const char *mode;
+{
+    char *path;         /* identifier for error messages */
+    gzFile gz;
+
+    if (fd == -1 || (path = malloc(7 + 3 * sizeof(int))) == NULL)
+        return NULL;
+    sprintf(path, "<fd:%d>", fd);   /* for debugging */
+    gz = gz_open(path, fd, mode);
+    free(path);
+    return gz;
+}
+
+/* -- see zlib.h -- */
+#ifdef _WIN32
+gzFile ZEXPORT gzopen_w(path, mode)
+    const wchar_t *path;
+    const char *mode;
+{
+    return gz_open(path, -2, mode);
+}
+#endif
+
+/* -- see zlib.h -- */
+int ZEXPORT gzbuffer(file, size)
+    gzFile file;
+    unsigned size;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* make sure we haven't already allocated memory */
+    if (state->size != 0)
+        return -1;
+
+    /* check and set requested size */
+    if (size < 2)
+        size = 2;               /* need two bytes to check magic header */
+    state->want = size;
+    return 0;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzrewind(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+
+    /* check that we're reading and that there's no error */
+    if (state->mode != GZ_READ ||
+            (state->err != Z_OK && state->err != Z_BUF_ERROR))
+        return -1;
+
+    /* back up and start over */
+    if (LSEEK(state->fd, state->start, SEEK_SET) == -1)
+        return -1;
+    gz_reset(state);
+    return 0;
+}
+
+/* -- see zlib.h -- */
+z_off64_t ZEXPORT gzseek64(file, offset, whence)
+    gzFile file;
+    z_off64_t offset;
+    int whence;
+{
+    unsigned n;
+    z_off64_t ret;
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* check that there's no error */
+    if (state->err != Z_OK && state->err != Z_BUF_ERROR)
+        return -1;
+
+    /* can only seek from start or relative to current position */
+    if (whence != SEEK_SET && whence != SEEK_CUR)
+        return -1;
+
+    /* normalize offset to a SEEK_CUR specification */
+    if (whence == SEEK_SET)
+        offset -= state->x.pos;
+    else if (state->seek)
+        offset += state->skip;
+    state->seek = 0;
+
+    /* if within raw area while reading, just go there */
+    if (state->mode == GZ_READ && state->how == COPY &&
+            state->x.pos + offset >= 0) {
+        ret = LSEEK(state->fd, offset - state->x.have, SEEK_CUR);
+        if (ret == -1)
+            return -1;
+        state->x.have = 0;
+        state->eof = 0;
+        state->past = 0;
+        state->seek = 0;
+        gz_error(state, Z_OK, NULL);
+        state->strm.avail_in = 0;
+        state->x.pos += offset;
+        return state->x.pos;
+    }
+
+    /* calculate skip amount, rewinding if needed for back seek when reading */
+    if (offset < 0) {
+        if (state->mode != GZ_READ)         /* writing -- can't go backwards */
+            return -1;
+        offset += state->x.pos;
+        if (offset < 0)                     /* before start of file! */
+            return -1;
+        if (gzrewind(file) == -1)           /* rewind, then skip to offset */
+            return -1;
+    }
+
+    /* if reading, skip what's in output buffer (one less gzgetc() check) */
+    if (state->mode == GZ_READ) {
+        n = GT_OFF(state->x.have) || (z_off64_t)state->x.have > offset ?
+            (unsigned)offset : state->x.have;
+        state->x.have -= n;
+        state->x.next += n;
+        state->x.pos += n;
+        offset -= n;
+    }
+
+    /* request skip (if not zero) */
+    if (offset) {
+        state->seek = 1;
+        state->skip = offset;
+    }
+    return state->x.pos + offset;
+}
+
+/* -- see zlib.h -- */
+z_off_t ZEXPORT gzseek(file, offset, whence)
+    gzFile file;
+    z_off_t offset;
+    int whence;
+{
+    z_off64_t ret;
+
+    ret = gzseek64(file, (z_off64_t)offset, whence);
+    return ret == (z_off_t)ret ? (z_off_t)ret : -1;
+}
+
+/* -- see zlib.h -- */
+z_off64_t ZEXPORT gztell64(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* return position */
+    return state->x.pos + (state->seek ? state->skip : 0);
+}
+
+/* -- see zlib.h -- */
+z_off_t ZEXPORT gztell(file)
+    gzFile file;
+{
+    z_off64_t ret;
+
+    ret = gztell64(file);
+    return ret == (z_off_t)ret ? (z_off_t)ret : -1;
+}
+
+/* -- see zlib.h -- */
+z_off64_t ZEXPORT gzoffset64(file)
+    gzFile file;
+{
+    z_off64_t offset;
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return -1;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return -1;
+
+    /* compute and return effective offset in file */
+    offset = LSEEK(state->fd, 0, SEEK_CUR);
+    if (offset == -1)
+        return -1;
+    if (state->mode == GZ_READ)             /* reading */
+        offset -= state->strm.avail_in;     /* don't count buffered input */
+    return offset;
+}
+
+/* -- see zlib.h -- */
+z_off_t ZEXPORT gzoffset(file)
+    gzFile file;
+{
+    z_off64_t ret;
+
+    ret = gzoffset64(file);
+    return ret == (z_off_t)ret ? (z_off_t)ret : -1;
+}
+
+/* -- see zlib.h -- */
+int ZEXPORT gzeof(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return 0;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return 0;
+
+    /* return end-of-file state */
+    return state->mode == GZ_READ ? state->past : 0;
+}
+
+/* -- see zlib.h -- */
+const char * ZEXPORT gzerror(file, errnum)
+    gzFile file;
+    int *errnum;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return NULL;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return NULL;
+
+    /* return error information */
+    if (errnum != NULL)
+        *errnum = state->err;
+    return state->msg == NULL ? "" : state->msg;
+}
+
+/* -- see zlib.h -- */
+void ZEXPORT gzclearerr(file)
+    gzFile file;
+{
+    gz_statep state;
+
+    /* get internal structure and check integrity */
+    if (file == NULL)
+        return;
+    state = (gz_statep)file;
+    if (state->mode != GZ_READ && state->mode != GZ_WRITE)
+        return;
+
+    /* clear error and end-of-file */
+    if (state->mode == GZ_READ) {
+        state->eof = 0;
+        state->past = 0;
+    }
+    gz_error(state, Z_OK, NULL);
+}
+
+/* Create an error message in allocated memory and set state->err and
+   state->msg accordingly.  Free any previous error message already there.  Do
+   not try to free or allocate space if the error is Z_MEM_ERROR (out of
+   memory).  Simply save the error message as a static string.  If there is an
+   allocation failure constructing the error message, then convert the error to
+   out of memory. */
+void ZLIB_INTERNAL gz_error(state, err, msg)
+    gz_statep state;
+    int err;
+    const char *msg;
+{
+    /* free previously allocated message and clear */
+    if (state->msg != NULL) {
+        if (state->err != Z_MEM_ERROR)
+            free(state->msg);
+        state->msg = NULL;
+    }
+
+    /* if fatal, set state->x.have to 0 so that the gzgetc() macro fails */
+    if (err != Z_OK && err != Z_BUF_ERROR)
+        state->x.have = 0;
+
+    /* set error code, and if no message, then done */
+    state->err = err;
+    if (msg == NULL)
+        return;
+
+    /* for an out of memory error, save as static string */
+    if (err == Z_MEM_ERROR) {
+        state->msg = (char *)msg;
+        return;
+    }
+
+    /* construct error message with path */
+    if ((state->msg = malloc(strlen(state->path) + strlen(msg) + 3)) == NULL) {
+        state->err = Z_MEM_ERROR;
+        state->msg = (char *)"out of memory";
+        return;
+    }
+    strcpy(state->msg, state->path);
+    strcat(state->msg, ": ");
+    strcat(state->msg, msg);
+    return;
+}
+
+#ifndef INT_MAX
+/* portably return maximum value for an int (when limits.h presumed not
+   available) -- we need to do this to cover cases where 2's complement not
+   used, since C standard permits 1's complement and sign-bit representations,
+   otherwise we could just use ((unsigned)-1) >> 1 */
+unsigned ZLIB_INTERNAL gz_intmax()
+{
+    unsigned p, q;
+
+    p = 1;
+    do {
+        q = p;
+        p <<= 1;
+        p++;
+    } while (p > q);
+    return q >> 1;
+}
+#endif