/**************************************************************************** * libc/stdio/lib_fopen.c * * Copyright (C) 2007-2012 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include "lib_internal.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Open mode flags */ #define MODE_R (1 << 0) /* Bit 0: "r{b|x|+}" open for reading */ #define MODE_W (1 << 1) /* Bit 1: "w{b|x|+}" open for writing, truncating, * or creating file */ #define MODE_A (1 << 2) /* Bit 2: "a{b|x|+}" open for writing, appending * the to file */ #define MODE_PLUS (1 << 3) /* Bit 3: "{r|w|a|b|x}+" open for update (reading * and writing) */ #define MODE_B (1 << 4) /* Bit 4: "{r|w|a|x|+}b" Binary mode */ #define MODE_X (1 << 5) /* Bit 5: "{r|w|a|b|+}x" Open exclusive mode */ #define MODE_NONE 0 /* No access mode determined */ #define MODE_MASK (MODE_R | MODE_W | MODE_A) /**************************************************************************** * Private Types ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: lib_mode2oflags ****************************************************************************/ static int lib_mode2oflags(FAR const char *mode) { unsigned int state; int oflags; /* Verify that a mode string was provided. */ DEBUGASSERT(mode); /* Parse the mode string to determine the corresponding open flags */ state = MODE_NONE; oflags = 0; for (; *mode; mode++) { switch (*mode) { /* Open for read access ("r{b|x|+}") */ case 'r' : if (state == MODE_NONE) { /* Open for read access */ oflags = O_RDOK; state = MODE_R; } else { goto errout; } break; /* Open for write access ("w{b|x|+}") */ case 'w' : if (state == MODE_NONE) { /* Open for write access, truncating any existing file */ oflags = (O_WROK | O_CREAT | O_TRUNC); state = MODE_W; } else { goto errout; } break; /* Open for write/append access ("a{b|x|+}") */ case 'a' : if (state == MODE_NONE) { /* Write to the end of the file */ oflags = O_WROK|O_CREAT|O_APPEND; state = MODE_A; } else { goto errout; } break; /* Open for update access ("{r|w|a|b|x}+") */ case '+' : switch (state & MODE_MASK) { case MODE_R: { /* Retain any binary and exclusive mode selections */ oflags &= (O_BINARY | O_EXCL); /* Open for read/write access */ oflags |= O_RDWR; state |= MODE_PLUS; } break; case MODE_W: { /* Retain any binary and exclusive mode selections */ oflags &= (O_BINARY | O_EXCL); /* Open for write read/access, truncating any existing file */ oflags |= (O_RDWR | O_CREAT | O_TRUNC); state |= MODE_PLUS; } break; case MODE_A: { /* Retain any binary and exclusive mode selections */ oflags &= (O_BINARY | O_EXCL); /* Read from the beginning of the file; write to the end */ oflags |= (O_RDWR | O_CREAT | O_APPEND); state |= MODE_PLUS; } break; default: goto errout; break; } break; /* Open for binary access ("{r|w|a|x|+}b") */ case 'b' : if ((state & MODE_MASK) != MODE_NONE) { /* The file is opened in binary mode */ oflags |= O_BINARY; state |= MODE_B; } else { goto errout; } break; /* Open for exclusive access ("{r|w|a|b|+}x") */ case 'X' : if ((state & MODE_MASK) != MODE_NONE) { /* The file is opened in exclusive mode */ oflags |= O_EXCL; state |= MODE_X; } else { goto errout; } break; /* Unrecognized or unsupported mode */ default: goto errout; break; } } return oflags; /* Both fopen and fdopen should fail with errno == EINVAL if the mode * string is invalid. */ errout: set_errno(EINVAL); return ERROR; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: fdopen ****************************************************************************/ FAR FILE *fdopen(int fd, FAR const char *mode) { FAR FILE *ret = NULL; int oflags; /* Map the open mode string to open flags */ oflags = lib_mode2oflags(mode); if (oflags >= 0) { ret = fs_fdopen(fd, oflags, NULL); } return ret; } /**************************************************************************** * Name: fopen ****************************************************************************/ FAR FILE *fopen(FAR const char *path, FAR const char *mode) { FAR FILE *ret = NULL; int oflags; int fd; /* Map the open mode string to open flags */ oflags = lib_mode2oflags(mode); if (oflags < 0) { return NULL; } /* Open the file */ fd = open(path, oflags, 0666); /* If the open was successful, then fdopen() the fil using the file * desciptor returned by open. If open failed, then just return the * NULL stream -- open() has already set the errno. */ if (fd >= 0) { ret = fs_fdopen(fd, oflags, NULL); if (!ret) { /* Don't forget to close the file descriptor if any other * failures are reported by fdopen(). */ (void)close(fd); } } return ret; }