X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=arch%2Fum%2Fos-Linux%2Fmem.c;fp=arch%2Fum%2Fos-Linux%2Fmem.c;h=4203681e508d0a680635347c53a2168fdd3a68be;hb=97bf2856c6014879bd04983a3e9dfcdac1e7fe85;hp=9d7d69a523bb551f069898bed0f2f2be7c4ef247;hpb=76828883507a47dae78837ab5dec5a5b4513c667;p=linux-2.6.git diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c index 9d7d69a52..4203681e5 100644 --- a/arch/um/os-Linux/mem.c +++ b/arch/um/os-Linux/mem.c @@ -8,6 +8,7 @@ #include #include #include +#include #include "kern_util.h" #include "user.h" #include "user_util.h" @@ -19,6 +20,7 @@ #include +static char *default_tmpdir = "/tmp"; static char *tempdir = NULL; static void __init find_tempdir(void) @@ -34,7 +36,7 @@ static void __init find_tempdir(void) break; } if((dir == NULL) || (*dir == '\0')) - dir = "/tmp"; + dir = default_tmpdir; tempdir = malloc(strlen(dir) + 2); if(tempdir == NULL){ @@ -46,6 +48,110 @@ static void __init find_tempdir(void) strcat(tempdir, "/"); } +/* This will return 1, with the first character in buf being the + * character following the next instance of c in the file. This will + * read the file as needed. If there's an error, -errno is returned; + * if the end of the file is reached, 0 is returned. + */ +static int next(int fd, char *buf, int size, char c) +{ + int n, len; + char *ptr; + + while((ptr = strchr(buf, c)) == NULL){ + n = read(fd, buf, size - 1); + if(n == 0) + return 0; + else if(n < 0) + return -errno; + + buf[n] = '\0'; + } + + ptr++; + len = strlen(ptr); + memmove(buf, ptr, len + 1); + + /* Refill the buffer so that if there's a partial string that we care + * about, it will be completed, and we can recognize it. + */ + n = read(fd, &buf[len], size - len - 1); + if(n < 0) + return -errno; + + buf[len + n] = '\0'; + return 1; +} + +static int checked_tmpdir = 0; + +/* Look for a tmpfs mounted at /dev/shm. I couldn't find a cleaner + * way to do this than to parse /proc/mounts. statfs will return the + * same filesystem magic number and fs id for both /dev and /dev/shm + * when they are both tmpfs, so you can't tell if they are different + * filesystems. Also, there seems to be no other way of finding the + * mount point of a filesystem from within it. + * + * If a /dev/shm tmpfs entry is found, then we switch to using it. + * Otherwise, we stay with the default /tmp. + */ +static void which_tmpdir(void) +{ + int fd, found; + char buf[128] = { '\0' }; + + if(checked_tmpdir) + return; + + checked_tmpdir = 1; + + printf("Checking for tmpfs mount on /dev/shm..."); + + fd = open("/proc/mounts", O_RDONLY); + if(fd < 0){ + printf("failed to open /proc/mounts, errno = %d\n", errno); + return; + } + + while(1){ + found = next(fd, buf, ARRAY_SIZE(buf), ' '); + if(found != 1) + break; + + if(!strncmp(buf, "/dev/shm", strlen("/dev/shm"))) + goto found; + + found = next(fd, buf, ARRAY_SIZE(buf), '\n'); + if(found != 1) + break; + } + +err: + if(found == 0) + printf("nothing mounted on /dev/shm\n"); + else if(found < 0) + printf("read returned errno %d\n", -found); + +out: + close(fd); + + return; + +found: + found = next(fd, buf, ARRAY_SIZE(buf), ' '); + if(found != 1) + goto err; + + if(strncmp(buf, "tmpfs", strlen("tmpfs"))){ + printf("not tmpfs\n"); + goto out; + } + + printf("OK\n"); + default_tmpdir = "/dev/shm"; + goto out; +} + /* * This proc still used in tt-mode * (file: kernel/tt/ptproxy/proxy.c, proc: start_debugger). @@ -53,33 +159,37 @@ static void __init find_tempdir(void) */ int make_tempfile(const char *template, char **out_tempname, int do_unlink) { - char tempname[MAXPATHLEN]; + char *tempname; int fd; + which_tmpdir(); + tempname = malloc(MAXPATHLEN); + find_tempdir(); - if (*template != '/') + if (template[0] != '/') strcpy(tempname, tempdir); else - *tempname = 0; + tempname[0] = '\0'; strcat(tempname, template); fd = mkstemp(tempname); if(fd < 0){ fprintf(stderr, "open - cannot create %s: %s\n", tempname, strerror(errno)); - return -1; + goto out; } if(do_unlink && (unlink(tempname) < 0)){ perror("unlink"); - return -1; + goto out; } if(out_tempname){ - *out_tempname = strdup(tempname); - if(*out_tempname == NULL){ - perror("strdup"); - return -1; - } + *out_tempname = tempname; + } else { + free(tempname); } return(fd); +out: + free(tempname); + return -1; } #define TEMPNAME_TEMPLATE "vm_file-XXXXXX" @@ -104,8 +214,11 @@ int create_tmp_file(unsigned long long len) exit(1); } - if (lseek64(fd, len, SEEK_SET) < 0) { - perror("os_seek_file"); + /* Seek to len - 1 because writing a character there will + * increase the file size by one byte, to the desired length. + */ + if (lseek64(fd, len - 1, SEEK_SET) < 0) { + perror("os_seek_file"); exit(1); } @@ -121,36 +234,11 @@ int create_tmp_file(unsigned long long len) return(fd); } -static int create_anon_file(unsigned long long len) -{ - void *addr; - int fd; - - fd = open("/dev/anon", O_RDWR); - if(fd < 0) { - perror("opening /dev/anon"); - exit(1); - } - - addr = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0); - if(addr == MAP_FAILED){ - perror("mapping physmem file"); - exit(1); - } - munmap(addr, len); - - return(fd); -} - -extern int have_devanon; - int create_mem_file(unsigned long long len) { int err, fd; - if(have_devanon) - fd = create_anon_file(len); - else fd = create_tmp_file(len); + fd = create_tmp_file(len); err = os_set_exec_close(fd, 1); if(err < 0){ @@ -159,3 +247,26 @@ int create_mem_file(unsigned long long len) } return(fd); } + + +void check_tmpexec(void) +{ + void *addr; + int err, fd = create_tmp_file(UM_KERN_PAGE_SIZE); + + addr = mmap(NULL, UM_KERN_PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE, fd, 0); + printf("Checking PROT_EXEC mmap in %s...",tempdir); + fflush(stdout); + if(addr == MAP_FAILED){ + err = errno; + perror("failed"); + if(err == EPERM) + printf("%s must be not mounted noexec\n",tempdir); + exit(1); + } + printf("OK\n"); + munmap(addr, UM_KERN_PAGE_SIZE); + + close(fd); +}