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Diffstat (limited to 'libpng/pngrio.c')
| -rw-r--r-- | libpng/pngrio.c | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/libpng/pngrio.c b/libpng/pngrio.c new file mode 100644 index 0000000..79755b4 --- /dev/null +++ b/libpng/pngrio.c @@ -0,0 +1,161 @@ + +/* pngrio.c - functions for data input + * + * libpng 1.2.1 - December 12, 2001 + * For conditions of distribution and use, see copyright notice in png.h + * Copyright (c) 1998-2001 Glenn Randers-Pehrson + * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) + * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) + * + * This file provides a location for all input. Users who need + * special handling are expected to write a function that has the same + * arguments as this and performs a similar function, but that possibly + * has a different input method. Note that you shouldn't change this + * function, but rather write a replacement function and then make + * libpng use it at run time with png_set_read_fn(...). + */ + +#define PNG_INTERNAL +#include "png.h" + +/* Read the data from whatever input you are using. The default routine + reads from a file pointer. Note that this routine sometimes gets called + with very small lengths, so you should implement some kind of simple + buffering if you are using unbuffered reads. This should never be asked + to read more then 64K on a 16 bit machine. */ +void /* PRIVATE */ +png_read_data(png_structp png_ptr, png_bytep data, png_size_t length) +{ + png_debug1(4,"reading %d bytes\n", (int)length); + if (png_ptr->read_data_fn != NULL) + (*(png_ptr->read_data_fn))(png_ptr, data, length); + else + png_error(png_ptr, "Call to NULL read function"); +} + +#if !defined(PNG_NO_STDIO) +/* This is the function that does the actual reading of data. If you are + not reading from a standard C stream, you should create a replacement + read_data function and use it at run time with png_set_read_fn(), rather + than changing the library. */ +#ifndef USE_FAR_KEYWORD +static void /* PRIVATE */ +png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length) +{ + png_size_t check; + + /* fread() returns 0 on error, so it is OK to store this in a png_size_t + * instead of an int, which is what fread() actually returns. + */ +#if defined(_WIN32_WCE) + if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) + check = 0; +#else + check = (png_size_t)fread(data, (png_size_t)1, length, + (png_FILE_p)png_ptr->io_ptr); +#endif + + if (check != length) + png_error(png_ptr, "Read Error"); +} +#else +/* this is the model-independent version. Since the standard I/O library + can't handle far buffers in the medium and small models, we have to copy + the data. +*/ + +#define NEAR_BUF_SIZE 1024 +#define MIN(a,b) (a <= b ? a : b) + +static void /* PRIVATE */ +png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length) +{ + int check; + png_byte *n_data; + png_FILE_p io_ptr; + + /* Check if data really is near. If so, use usual code. */ + n_data = (png_byte *)CVT_PTR_NOCHECK(data); + io_ptr = (png_FILE_p)CVT_PTR(png_ptr->io_ptr); + if ((png_bytep)n_data == data) + { +#if defined(_WIN32_WCE) + if ( !ReadFile((HANDLE)(png_ptr->io_ptr), data, length, &check, NULL) ) + check = 0; +#else + check = fread(n_data, 1, length, io_ptr); +#endif + } + else + { + png_byte buf[NEAR_BUF_SIZE]; + png_size_t read, remaining, err; + check = 0; + remaining = length; + do + { + read = MIN(NEAR_BUF_SIZE, remaining); +#if defined(_WIN32_WCE) + if ( !ReadFile((HANDLE)(io_ptr), buf, read, &err, NULL) ) + err = 0; +#else + err = fread(buf, (png_size_t)1, read, io_ptr); +#endif + png_memcpy(data, buf, read); /* copy far buffer to near buffer */ + if(err != read) + break; + else + check += err; + data += read; + remaining -= read; + } + while (remaining != 0); + } + if ((png_uint_32)check != (png_uint_32)length) + png_error(png_ptr, "read Error"); +} +#endif +#endif + +/* This function allows the application to supply a new input function + for libpng if standard C streams aren't being used. + + This function takes as its arguments: + png_ptr - pointer to a png input data structure + io_ptr - pointer to user supplied structure containing info about + the input functions. May be NULL. + read_data_fn - pointer to a new input function that takes as its + arguments a pointer to a png_struct, a pointer to + a location where input data can be stored, and a 32-bit + unsigned int that is the number of bytes to be read. + To exit and output any fatal error messages the new write + function should call png_error(png_ptr, "Error msg"). */ +void PNGAPI +png_set_read_fn(png_structp png_ptr, png_voidp io_ptr, + png_rw_ptr read_data_fn) +{ + png_ptr->io_ptr = io_ptr; + +#if !defined(PNG_NO_STDIO) + if (read_data_fn != NULL) + png_ptr->read_data_fn = read_data_fn; + else + png_ptr->read_data_fn = png_default_read_data; +#else + png_ptr->read_data_fn = read_data_fn; +#endif + + /* It is an error to write to a read device */ + if (png_ptr->write_data_fn != NULL) + { + png_ptr->write_data_fn = NULL; + png_warning(png_ptr, + "It's an error to set both read_data_fn and write_data_fn in the "); + png_warning(png_ptr, + "same structure. Resetting write_data_fn to NULL."); + } + +#if defined(PNG_WRITE_FLUSH_SUPPORTED) + png_ptr->output_flush_fn = NULL; +#endif +} |