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Hi all, This patch adds shm_open() and shm_unlink() to librt. For my own purposes, I have git'ed uclibc and made the patch from there, so let me know if you need it in another format. The included testapp simply creates shared memory area in a parent process, writes test data to it and opens and verifies the data in a forked child process. Thanks, Mikael Carmelo AMOROSO skrev: Mikael Lund Jepsen, ICCC wrote: --
 Mikael Lund Jepsen, Software Engineer ICCC A/S, Telegrafvej 5 B, 2750 Ballerup, DENMARK
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#include <errno.h> #include <fcntl.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/wait.h>
char Commonname[] = "MyTestMem";
int TestData[11] = {0,1,2,3,4,5,6,7,8,9,10};
int main(void) {
int pfds[2];
pid_t pid;
int hCommon;
int TestdataFails = 0;
char *pTestData;
unsigned int i;
char buf[30];
int rv;
pipe(pfds);
switch(pid = fork()) {
case -1:
perror("fork");
exit(1); // parent exits
case 0:
// Child
// wait for parent
read(pfds[0], buf, 5);
hCommon = shm_open(Commonname, O_RDWR, DEFFILEMODE);
if (hCommon == -1) {
perror("CHILD - shm_open(existing):");
exit(1);
} else {
pTestData = mmap(0, sizeof(TestData), PROT_READ +
PROT_WRITE, MAP_SHARED, hCommon, 0);
if (pTestData != MAP_FAILED) {
for (i=0; i < sizeof(TestData); i++) {
if (pTestData[i] != TestData[i]) {
printf("%-40s: Offset %d, local
%d, shm %d", "Compare memory error", i, TestData[i], pTestData[i]);
TestdataFails++;
}
}
if (TestdataFails == 0)
printf("%-40s: %s\n", "Compare memory",
"Success");
munmap(pTestData, sizeof(TestData));
}
}
exit(0);
default:
// Parent
hCommon = shm_open(Commonname, O_RDWR+O_CREAT+O_EXCL,
DEFFILEMODE );
if (hCommon == -1) {
perror("PARENT - shm_open(create):");
} else {
if ((ftruncate(hCommon, sizeof(TestData))) == -1)
{
printf("%-40s: %s", "ftruncate",
strerror(errno));
shm_unlink(Commonname);
return 0;
}
pTestData = mmap(0, sizeof(TestData), PROT_READ +
PROT_WRITE, MAP_SHARED, hCommon, 0);
if (pTestData == MAP_FAILED)
{
perror("PARENT - mmap:");
if (shm_unlink(Commonname) == -1) {
perror("PARENT - shm_unklink:");
}
return 0;
}
for (i=0; i <sizeof(TestData); i++)
pTestData[i] = TestData[i];
// signal child
write(pfds[1], "rdy", 5);
// wait for child
wait(&rv);
// Cleanup
munmap(pTestData, sizeof(TestData));
if (shm_unlink(Commonname) == -1) {
perror("PARENT - shm_unklink:");
}
}
}
return 0;
}
commit 941e902888017dcd798c4ba61d5a702085d806f9 Author: Mikael Lund Jepsen <[email protected]> Date: Wed Jan 14 20:17:30 2009 +0100 Add shm_open.c and shm_unlink.c to librt. Original source: sourceware.org/newlib, CVS snapshot 2009-01-14 diff --git a/librt/shm_open.c b/librt/shm_open.c new file mode 100644 index 0000000..cb92c3a --- /dev/null +++ b/librt/shm_open.c @@ -0,0 +1,48 @@ +/* shm_open - open a shared memory file */ + +/* Copyright 2002, Red Hat Inc. */ + +#include <sys/types.h> +#include <sys/mman.h> +#include <unistd.h> +#include <string.h> +#include <fcntl.h> +#include <limits.h> + +int +shm_open (const char *name, int oflag, mode_t mode) +{ + int fd; + char shm_name[PATH_MAX+20] = "/dev/shm/"; + + /* skip opening slash */ + if (*name == '/') + ++name; + + /* create special shared memory file name and leave enough space to + cause a path/name error if name is too long */ + strlcpy (shm_name + 9, name, PATH_MAX + 10); + + fd = open (shm_name, oflag, mode); + + if (fd != -1) + { + /* once open we must add FD_CLOEXEC flag to file descriptor */ + int flags = fcntl (fd, F_GETFD, 0); + + if (flags >= 0) + { + flags |= FD_CLOEXEC; + flags = fcntl (fd, F_SETFD, flags); + } + + /* on failure, just close file and give up */ + if (flags == -1) + { + close (fd); + fd = -1; + } + } + + return fd; +} diff --git a/librt/shm_unlink.c b/librt/shm_unlink.c new file mode 100644 index 0000000..cf259c6 --- /dev/null +++ b/librt/shm_unlink.c @@ -0,0 +1,28 @@ +/* shm_unlink - remove a shared memory file */ + +/* Copyright 2002, Red Hat Inc. */ + +#include <sys/types.h> +#include <sys/mman.h> +#include <unistd.h> +#include <string.h> +#include <limits.h> + +int +shm_unlink (const char *name) +{ + int rc; + char shm_name[PATH_MAX+20] = "/dev/shm/"; + + /* skip opening slash */ + if (*name == '/') + ++name; + + /* create special shared memory file name and leave enough space to + cause a path/name error if name is too long */ + strlcpy (shm_name + 9, name, PATH_MAX + 10); + + rc = unlink (shm_name); + + return rc; +}
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