src/rt/RdataShareFile.cpp

#ifndef lint
static const char RCSid[] = "$Id: RdataShareFile.cpp,v 2.3 2024/12/09 22:26:01 greg Exp $";
#endif
/*
 *  RdataShareFile.cpp
 *
 *      Shared data using a regular file
 *
 *  Created by Greg Ward on 10/14/2024
 */

#include "rtio.h"
#include "rterror.h"
#include "RdataShare.h"
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>

const char      RDSnoname[] = "<unnamed_channel>";

RdataShare::~RdataShare()
{
        freeqstr(chName);
}

// Struct needed for tracking allocated buffers
struct RDSbuffer {
        RDSbuffer *     next;                   // next in list
        char *          buf;                    // allocated buffer
        size_t          len;                    // buffer length
        off_t           pos;                    // offset in file

                        RDSbuffer(size_t nb, RDSbuffer *nxt = NULL);
                        ~RDSbuffer() {
                                delete next;
                                if (len > 0) free(buf);
                        }
                        /// Find buffer matching pointer
        RDSbuffer *     Find(void *p) {
                                RDSbuffer *     bp = this;
                                while (p != (void *)bp->buf &&
                                                (bp = bp->next) != NULL)
                                        ;
                                return bp;
                        }
};

// Allocate an i/o buffer
RDSbuffer::RDSbuffer(size_t nb, RDSbuffer *nxt)
{
        next = nxt;
        buf = NULL;
        pos = -1;
        if ((len = nb) > 0) {
                buf = (char *)malloc(nb);
                if (!buf) {
                        sprintf(errmsg, "cannot allocate %lu-byte buffer",
                                        (unsigned long)nb);
                        error(SYSTEM, errmsg);
                        len = 0;
                        return;
                }
        }
}

// Create memory-mapped file object
RdataShareFile::RdataShareFile(const char *name, int flags, size_t siz)
{
        fd = -1;
        blist = NULL;

        if (!name || !*name) {
                error(CONSISTENCY, "missing file name in RdataShareFile()");
                return;
        }
        if (!(flags & (RDSread|RDSwrite))) {
                error(CONSISTENCY, "RdataShareFile() flags must include RDSread or RDSwrite");
                return;
        }
        if ((flags & (RDSextend|RDSwrite)) == RDSextend) {
                error(CONSISTENCY, "bad RDSextend in RdataShareFile()");
                return;
        }
        int     oflags = O_CLOEXEC;
        switch (flags & (RDSread|RDSwrite)) {
        case RDSread|RDSwrite:
                oflags |= O_RDWR|O_CREAT;
                break;
        case RDSwrite:
                oflags |= O_WRONLY|O_CREAT;
                break;
        case RDSread:
                oflags |= O_RDONLY;
                break;
        }
        if (flags & RDSexcl) oflags |= O_EXCL;
        else if (flags & RDSextend && !siz) oflags |= O_TRUNC;
        fd = open(name, oflags, 0666);
        if (fd < 0) {
                sprintf(errmsg, "cannot open '%s'", name);
                error(SYSTEM, errmsg);
                return;
        }
        if (!(flags & RDSextend)) {
                struct stat     sbuf;
                if (flags & RDSexcl)
                        siz = 0;
                else if (fstat(fd, &sbuf) >= 0)
                        siz = sbuf.st_size;
                else  {
                        sprintf(errmsg, "cannot stat '%s'", name);
                        error(SYSTEM, errmsg);
                        close(fd); fd = -1;
                        return;
                }
        } else if (siz && ftruncate(fd, siz) < 0) {
                sprintf(errmsg, "cannot resize '%s'", name);
                error(SYSTEM, errmsg);
                close(fd); fd = -1;
                return;
        }
        osiz = siz;
        chName = savqstr(name);
        mode = flags;
}

RdataShareFile::~RdataShareFile()
{
        if (fd >= 0) close(fd);
        delete blist;
}

// Attempt to extend or shrink object (adjust if 0)
size_t
RdataShareFile::Resize(size_t new_siz)
{
        if (fd < 0)
                return 0;
        if (new_siz > 0) {
                if (new_siz == osiz)
                        return osiz;
                if (!(mode & RDSwrite)) {
                        error(CONSISTENCY, "cannot resize read-only file");
                        return 0;
                }
        } else {                        // sync to current file length
                struct stat     sbuf;
                if (fstat(fd, &sbuf) < 0) {
                        sprintf(errmsg, "cannot stat '%s'", chName);
                        error(SYSTEM, errmsg);
                        return 0;
                }
                return osiz = sbuf.st_size;
        }                               // else attempt to resize file
        if (ftruncate(fd, new_siz) < 0) {
                sprintf(errmsg, "cannot resize '%s'", chName);
                return 0;
        }
        return osiz = new_siz;
}

// Get data buffer
void *
RdataShareFile::GetMemory(size_t offs, size_t len, int fl)
{
        if (fd < 0)
                return NULL;
        if (fl & RDSextend && !Resize())        // sync to file length, first?
                return NULL;
        if (fl & mode & RDSread && offs + len > osiz) {
                if (fl & RDSextend) {   // resize if requested
                        if (!Resize(offs + len))
                                return NULL;
                } else {
                        sprintf(errmsg, "requested block of %lu bytes past EOF in '%s'",
                                                (unsigned long)len, chName);
                        error(CONSISTENCY, errmsg);
                        return NULL;
                }
        }                               // XXX should check for buffer overlap?
        blist = new RDSbuffer(len, blist);
        blist->pos = offs;
        if (fl & mode & RDSread &&      // reading from file?
                                pread(fd, blist->buf, len, offs) != len) {
                sprintf(errmsg, "read error on '%s'", chName);
                error(SYSTEM, errmsg);
        }
        return blist->buf;
}

// Return data buffer
bool
RdataShareFile::ReleaseMemory(void *dp, int fl)
{
        if (!blist) return false;
        RDSbuffer *     bp = blist->Find(dp);
        if (!bp) {
                sprintf(errmsg, "return of unallocated block for '%s'", chName);
                error(CONSISTENCY, errmsg);
                return false;
        }
        if ((fl & (RDSwrite|RDSextend)) == RDSwrite && bp->pos + bp->len > osiz) {
                sprintf(errmsg, "write request past EOF in '%s'", chName);
                error(CONSISTENCY, errmsg);
                return NULL;
        }
        if (fl & mode & RDSwrite) {     // writing to file?
                if (pwrite(fd, bp->buf, bp->len, bp->pos) != bp->len) {
                        sprintf(errmsg, "write error on '%s'", chName);
                        error(SYSTEM, errmsg);
                        return false;
                }
                if (bp->pos + bp->len > osiz)
                        osiz = bp->pos + bp->len;
        }
        RDSbuffer       rbuf(0, blist);         // remove from buffer list
        RDSbuffer *     bp2 = &rbuf;
        while (bp2->next != bp)
                bp2 = bp2->next;
        bp2->next = bp->next;
        bp->next = NULL;
        delete bp;                              // frees buffer memory
        blist = rbuf.next;
        return true;
}
Revision:	2.4
Committed:	Mon Oct 27 18:38:32 2025 UTC (7 days, 18 hours ago) by greg
Branch:	MAIN
CVS Tags:	HEAD
Changes since 2.3:	+2 -2 lines
Log Message:	fix(rxfluxmtx,rxcontrib): initial truncation of forced output overwrite
#	User	Rev	Content
1	greg	2.1	#ifndef lint
2	greg	2.4	static const char RCSid[] = "$Id: RdataShareFile.cpp,v 2.3 2024/12/09 22:26:01 greg Exp $";
3	greg	2.1	#endif
4			/*
5			* RdataShareFile.cpp
6			*
7			* Shared data using a regular file
8			*
9			* Created by Greg Ward on 10/14/2024
10			*/
11
12			#include "rtio.h"
13			#include "rterror.h"
14			#include "RdataShare.h"
15			#include <stdlib.h>
16			#include <unistd.h>
17			#include <sys/stat.h>
18
19			const char RDSnoname[] = "<unnamed_channel>";
20
21			RdataShare::~RdataShare()
22			{
23			freeqstr(chName);
24			}
25
26			// Struct needed for tracking allocated buffers
27			struct RDSbuffer {
28			RDSbuffer * next; // next in list
29			char * buf; // allocated buffer
30			size_t len; // buffer length
31			off_t pos; // offset in file
32
33			RDSbuffer(size_t nb, RDSbuffer *nxt = NULL);
34			~RDSbuffer() {
35			delete next;
36			if (len > 0) free(buf);
37			}
38			/// Find buffer matching pointer
39			RDSbuffer * Find(void *p) {
40			RDSbuffer * bp = this;
41			while (p != (void *)bp->buf &&
42			(bp = bp->next) != NULL)
43			;
44			return bp;
45			}
46			};
47
48			// Allocate an i/o buffer
49			RDSbuffer::RDSbuffer(size_t nb, RDSbuffer *nxt)
50			{
51			next = nxt;
52			buf = NULL;
53			pos = -1;
54			if ((len = nb) > 0) {
55			buf = (char *)malloc(nb);
56			if (!buf) {
57			sprintf(errmsg, "cannot allocate %lu-byte buffer",
58			(unsigned long)nb);
59			error(SYSTEM, errmsg);
60			len = 0;
61			return;
62			}
63			}
64			}
65
66			// Create memory-mapped file object
67			RdataShareFile::RdataShareFile(const char *name, int flags, size_t siz)
68			{
69			fd = -1;
70			blist = NULL;
71
72			if (!name \|\| !*name) {
73			error(CONSISTENCY, "missing file name in RdataShareFile()");
74			return;
75			}
76			if (!(flags & (RDSread\|RDSwrite))) {
77			error(CONSISTENCY, "RdataShareFile() flags must include RDSread or RDSwrite");
78			return;
79			}
80			if ((flags & (RDSextend\|RDSwrite)) == RDSextend) {
81			error(CONSISTENCY, "bad RDSextend in RdataShareFile()");
82			return;
83			}
84			int oflags = O_CLOEXEC;
85			switch (flags & (RDSread\|RDSwrite)) {
86			case RDSread\|RDSwrite:
87	greg	2.2	oflags \|= O_RDWR\|O_CREAT;
88			break;
89			case RDSwrite:
90			oflags \|= O_WRONLY\|O_CREAT;
91	greg	2.1	break;
92			case RDSread:
93			oflags \|= O_RDONLY;
94			break;
95			}
96	greg	2.2	if (flags & RDSexcl) oflags \|= O_EXCL;
97	greg	2.1	else if (flags & RDSextend && !siz) oflags \|= O_TRUNC;
98			fd = open(name, oflags, 0666);
99			if (fd < 0) {
100			sprintf(errmsg, "cannot open '%s'", name);
101			error(SYSTEM, errmsg);
102			return;
103			}
104			if (!(flags & RDSextend)) {
105			struct stat sbuf;
106			if (flags & RDSexcl)
107			siz = 0;
108			else if (fstat(fd, &sbuf) >= 0)
109			siz = sbuf.st_size;
110			else {
111	greg	2.3	sprintf(errmsg, "cannot stat '%s'", name);
112	greg	2.1	error(SYSTEM, errmsg);
113			close(fd); fd = -1;
114			return;
115			}
116			} else if (siz && ftruncate(fd, siz) < 0) {
117			sprintf(errmsg, "cannot resize '%s'", name);
118			error(SYSTEM, errmsg);
119			close(fd); fd = -1;
120			return;
121			}
122			osiz = siz;
123			chName = savqstr(name);
124			mode = flags;
125			}
126
127			RdataShareFile::~RdataShareFile()
128			{
129			if (fd >= 0) close(fd);
130			delete blist;
131			}
132
133			// Attempt to extend or shrink object (adjust if 0)
134			size_t
135			RdataShareFile::Resize(size_t new_siz)
136			{
137			if (fd < 0)
138			return 0;
139			if (new_siz > 0) {
140			if (new_siz == osiz)
141			return osiz;
142			if (!(mode & RDSwrite)) {
143			error(CONSISTENCY, "cannot resize read-only file");
144			return 0;
145			}
146			} else { // sync to current file length
147			struct stat sbuf;
148			if (fstat(fd, &sbuf) < 0) {
149			sprintf(errmsg, "cannot stat '%s'", chName);
150			error(SYSTEM, errmsg);
151			return 0;
152			}
153			return osiz = sbuf.st_size;
154			} // else attempt to resize file
155			if (ftruncate(fd, new_siz) < 0) {
156	greg	2.4	sprintf(errmsg, "cannot resize '%s'", chName);
157	greg	2.1	return 0;
158			}
159			return osiz = new_siz;
160			}
161
162			// Get data buffer
163			void *
164			RdataShareFile::GetMemory(size_t offs, size_t len, int fl)
165			{
166			if (fd < 0)
167			return NULL;
168			if (fl & RDSextend && !Resize()) // sync to file length, first?
169			return NULL;
170			if (fl & mode & RDSread && offs + len > osiz) {
171			if (fl & RDSextend) { // resize if requested
172			if (!Resize(offs + len))
173			return NULL;
174			} else {
175			sprintf(errmsg, "requested block of %lu bytes past EOF in '%s'",
176			(unsigned long)len, chName);
177			error(CONSISTENCY, errmsg);
178			return NULL;
179			}
180			} // XXX should check for buffer overlap?
181			blist = new RDSbuffer(len, blist);
182			blist->pos = offs;
183			if (fl & mode & RDSread && // reading from file?
184			pread(fd, blist->buf, len, offs) != len) {
185			sprintf(errmsg, "read error on '%s'", chName);
186			error(SYSTEM, errmsg);
187			}
188			return blist->buf;
189			}
190
191			// Return data buffer
192			bool
193			RdataShareFile::ReleaseMemory(void *dp, int fl)
194			{
195			if (!blist) return false;
196			RDSbuffer * bp = blist->Find(dp);
197			if (!bp) {
198			sprintf(errmsg, "return of unallocated block for '%s'", chName);
199			error(CONSISTENCY, errmsg);
200			return false;
201			}
202			if ((fl & (RDSwrite\|RDSextend)) == RDSwrite && bp->pos + bp->len > osiz) {
203			sprintf(errmsg, "write request past EOF in '%s'", chName);
204			error(CONSISTENCY, errmsg);
205			return NULL;
206			}
207			if (fl & mode & RDSwrite) { // writing to file?
208			if (pwrite(fd, bp->buf, bp->len, bp->pos) != bp->len) {
209			sprintf(errmsg, "write error on '%s'", chName);
210			error(SYSTEM, errmsg);
211			return false;
212			}
213			if (bp->pos + bp->len > osiz)
214			osiz = bp->pos + bp->len;
215			}
216			RDSbuffer rbuf(0, blist); // remove from buffer list
217			RDSbuffer * bp2 = &rbuf;
218			while (bp2->next != bp)
219			bp2 = bp2->next;
220			bp2->next = bp->next;
221			bp->next = NULL;
222			delete bp; // frees buffer memory
223			blist = rbuf.next;
224			return true;
225			}