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#ifndef lint |
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static const char RCSid[] = "$Id: RdataShareFile.cpp,v 2.1 2024/10/29 00:36:54 greg Exp $"; |
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#endif |
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/* |
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* RdataShareFile.cpp |
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* |
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* Shared data using a regular file |
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* |
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* Created by Greg Ward on 10/14/2024 |
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*/ |
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|
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#include "rtio.h" |
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#include "rterror.h" |
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#include "RdataShare.h" |
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#include <stdlib.h> |
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#include <unistd.h> |
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#include <sys/stat.h> |
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|
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const char RDSnoname[] = "<unnamed_channel>"; |
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|
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RdataShare::~RdataShare() |
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{ |
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freeqstr(chName); |
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} |
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|
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// Struct needed for tracking allocated buffers |
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struct RDSbuffer { |
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RDSbuffer * next; // next in list |
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char * buf; // allocated buffer |
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size_t len; // buffer length |
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off_t pos; // offset in file |
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|
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RDSbuffer(size_t nb, RDSbuffer *nxt = NULL); |
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~RDSbuffer() { |
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delete next; |
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if (len > 0) free(buf); |
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} |
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/// Find buffer matching pointer |
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RDSbuffer * Find(void *p) { |
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RDSbuffer * bp = this; |
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while (p != (void *)bp->buf && |
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(bp = bp->next) != NULL) |
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; |
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return bp; |
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} |
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}; |
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|
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// Allocate an i/o buffer |
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RDSbuffer::RDSbuffer(size_t nb, RDSbuffer *nxt) |
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{ |
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next = nxt; |
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buf = NULL; |
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pos = -1; |
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if ((len = nb) > 0) { |
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buf = (char *)malloc(nb); |
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if (!buf) { |
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sprintf(errmsg, "cannot allocate %lu-byte buffer", |
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(unsigned long)nb); |
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error(SYSTEM, errmsg); |
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len = 0; |
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return; |
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} |
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} |
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} |
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|
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// Create memory-mapped file object |
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RdataShareFile::RdataShareFile(const char *name, int flags, size_t siz) |
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{ |
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fd = -1; |
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blist = NULL; |
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|
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if (!name || !*name) { |
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error(CONSISTENCY, "missing file name in RdataShareFile()"); |
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return; |
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} |
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if (!(flags & (RDSread|RDSwrite))) { |
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error(CONSISTENCY, "RdataShareFile() flags must include RDSread or RDSwrite"); |
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return; |
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} |
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if ((flags & (RDSextend|RDSwrite)) == RDSextend) { |
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error(CONSISTENCY, "bad RDSextend in RdataShareFile()"); |
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return; |
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} |
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int oflags = O_CLOEXEC; |
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switch (flags & (RDSread|RDSwrite)) { |
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case RDSread|RDSwrite: |
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oflags |= O_RDWR|O_CREAT; |
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break; |
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case RDSwrite: |
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oflags |= O_WRONLY|O_CREAT; |
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break; |
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case RDSread: |
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oflags |= O_RDONLY; |
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break; |
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} |
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if (flags & RDSexcl) oflags |= O_EXCL; |
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else if (flags & RDSextend && !siz) oflags |= O_TRUNC; |
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fd = open(name, oflags, 0666); |
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if (fd < 0) { |
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sprintf(errmsg, "cannot open '%s'", name); |
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error(SYSTEM, errmsg); |
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return; |
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} |
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if (!(flags & RDSextend)) { |
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struct stat sbuf; |
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if (flags & RDSexcl) |
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siz = 0; |
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else if (fstat(fd, &sbuf) >= 0) |
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siz = sbuf.st_size; |
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else { |
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sprintf(errmsg, "cannot stat '%s'", chName); |
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error(SYSTEM, errmsg); |
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close(fd); fd = -1; |
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return; |
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} |
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} else if (siz && ftruncate(fd, siz) < 0) { |
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sprintf(errmsg, "cannot resize '%s'", name); |
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error(SYSTEM, errmsg); |
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close(fd); fd = -1; |
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return; |
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} |
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osiz = siz; |
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chName = savqstr(name); |
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mode = flags; |
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} |
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|
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RdataShareFile::~RdataShareFile() |
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{ |
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if (fd >= 0) close(fd); |
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delete blist; |
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} |
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|
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// Attempt to extend or shrink object (adjust if 0) |
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size_t |
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RdataShareFile::Resize(size_t new_siz) |
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{ |
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if (fd < 0) |
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return 0; |
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if (new_siz > 0) { |
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if (new_siz == osiz) |
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return osiz; |
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if (!(mode & RDSwrite)) { |
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error(CONSISTENCY, "cannot resize read-only file"); |
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return 0; |
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} |
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} else { // sync to current file length |
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struct stat sbuf; |
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if (fstat(fd, &sbuf) < 0) { |
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sprintf(errmsg, "cannot stat '%s'", chName); |
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error(SYSTEM, errmsg); |
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return 0; |
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} |
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return osiz = sbuf.st_size; |
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} // else attempt to resize file |
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if (ftruncate(fd, new_siz) < 0) { |
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sprintf(errmsg, "cannot truncate '%s'", chName); |
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return 0; |
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} |
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return osiz = new_siz; |
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} |
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|
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// Get data buffer |
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void * |
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RdataShareFile::GetMemory(size_t offs, size_t len, int fl) |
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{ |
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if (fd < 0) |
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return NULL; |
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if (fl & RDSextend && !Resize()) // sync to file length, first? |
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return NULL; |
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if (fl & mode & RDSread && offs + len > osiz) { |
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if (fl & RDSextend) { // resize if requested |
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if (!Resize(offs + len)) |
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return NULL; |
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} else { |
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sprintf(errmsg, "requested block of %lu bytes past EOF in '%s'", |
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(unsigned long)len, chName); |
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error(CONSISTENCY, errmsg); |
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return NULL; |
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} |
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} // XXX should check for buffer overlap? |
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blist = new RDSbuffer(len, blist); |
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blist->pos = offs; |
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if (fl & mode & RDSread && // reading from file? |
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pread(fd, blist->buf, len, offs) != len) { |
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sprintf(errmsg, "read error on '%s'", chName); |
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error(SYSTEM, errmsg); |
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} |
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return blist->buf; |
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} |
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|
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// Return data buffer |
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bool |
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RdataShareFile::ReleaseMemory(void *dp, int fl) |
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{ |
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if (!blist) return false; |
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RDSbuffer * bp = blist->Find(dp); |
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if (!bp) { |
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sprintf(errmsg, "return of unallocated block for '%s'", chName); |
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error(CONSISTENCY, errmsg); |
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return false; |
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} |
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if ((fl & (RDSwrite|RDSextend)) == RDSwrite && bp->pos + bp->len > osiz) { |
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sprintf(errmsg, "write request past EOF in '%s'", chName); |
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error(CONSISTENCY, errmsg); |
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return NULL; |
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} |
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if (fl & mode & RDSwrite) { // writing to file? |
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if (pwrite(fd, bp->buf, bp->len, bp->pos) != bp->len) { |
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sprintf(errmsg, "write error on '%s'", chName); |
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error(SYSTEM, errmsg); |
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return false; |
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} |
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if (bp->pos + bp->len > osiz) |
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osiz = bp->pos + bp->len; |
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} |
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RDSbuffer rbuf(0, blist); // remove from buffer list |
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RDSbuffer * bp2 = &rbuf; |
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while (bp2->next != bp) |
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bp2 = bp2->next; |
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bp2->next = bp->next; |
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bp->next = NULL; |
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delete bp; // frees buffer memory |
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blist = rbuf.next; |
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return true; |
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} |
