[PATCH libpciaccess] Allow building without O_CLOEXEC

Jasper St. Pierre jstpierre at mecheye.net
Mon Sep 22 12:56:40 PDT 2014


How old? O_CLOEXEC is part of the 2008 POSIX specification. I really
wouldn't like to build on anything older than that... :(

On Mon, Sep 22, 2014 at 1:24 PM, Aaron Plattner <aplattner at nvidia.com>
wrote:

> Old versions of Linux don't support O_CLOEXEC, so rather than failing to
> build,
> allow building without O_CLOEXEC if a new ALLOW_NO_O_CLOEXEC flag is
> defined.
>
> Create a new helper function, pci_open_cloexec that uses O_CLOEXEC when
> it's
> available and falls back to open + fcntl when it's not.  Route all calls
> to open
> that pass O_CLOEXEC through this new function instead using the following
> Coccinelle patch:
>
>   @@
>   expression path, flags;
>   @@
>   -open(path, flags | O_CLOEXEC)
>   +pci_open_cloexec(path, flags)
>
> Signed-off-by: Aaron Plattner <aplattner at nvidia.com>
> ---
> There are three calls to open() that don't use O_CLOEXEC -- are those bugs?
>
> src/linux_devmem.c:    fd = open("/dev/mem", O_RDONLY, 0);
> src/netbsd_pci.c:       fd = open("/dev/ttyE0", O_RDONLY);
> src/netbsd_pci.c:               pcifd = open(netbsd_devname, O_RDWR);
>
>  src/common_vgaarb.c     |  2 +-
>  src/freebsd_pci.c       | 10 +++++-----
>  src/linux_sysfs.c       | 26 +++++++++++++-------------
>  src/netbsd_pci.c        |  2 +-
>  src/openbsd_pci.c       |  2 +-
>  src/pciaccess_private.h | 33 +++++++++++++++++++++++++++++----
>  src/solx_devfs.c        |  4 ++--
>  src/x86_pci.c           |  4 ++--
>  8 files changed, 54 insertions(+), 29 deletions(-)
>
> diff --git a/src/common_vgaarb.c b/src/common_vgaarb.c
> index c59bd788dc5e..f3b523e67c3a 100644
> --- a/src/common_vgaarb.c
> +++ b/src/common_vgaarb.c
> @@ -131,7 +131,7 @@ pci_device_vgaarb_init(void)
>      if (!pci_sys)
>          return -1;
>
> -    if ((pci_sys->vgaarb_fd = open ("/dev/vga_arbiter", O_RDWR |
> O_CLOEXEC)) < 0) {
> +    if ((pci_sys->vgaarb_fd = pci_open_cloexec ("/dev/vga_arbiter",
> O_RDWR)) < 0) {
>          return errno;
>      }
>
> diff --git a/src/freebsd_pci.c b/src/freebsd_pci.c
> index 9505a1c17d21..e40d80847bf0 100644
> --- a/src/freebsd_pci.c
> +++ b/src/freebsd_pci.c
> @@ -112,7 +112,7 @@ pci_device_freebsd_map_range(struct pci_device *dev,
>
>      int fd, err = 0;
>
> -    fd = open("/dev/mem", O_RDWR | O_CLOEXEC);
> +    fd = pci_open_cloexec("/dev/mem", O_RDWR);
>      if (fd == -1)
>         return errno;
>
> @@ -157,7 +157,7 @@ pci_device_freebsd_unmap_range( struct pci_device *dev,
>      if ((map->flags & PCI_DEV_MAP_FLAG_CACHABLE) ||
>         (map->flags & PCI_DEV_MAP_FLAG_WRITE_COMBINE))
>      {
> -       fd = open("/dev/mem", O_RDWR | O_CLOEXEC);
> +       fd = pci_open_cloexec("/dev/mem", O_RDWR);
>         if (fd != -1) {
>             mrd.mr_base = map->base;
>             mrd.mr_len = map->size;
> @@ -297,7 +297,7 @@ pci_device_freebsd_read_rom( struct pci_device * dev,
> void * buffer )
>      }
>
>      printf("Using rom_base = 0x%lx\n", (long)rom_base);
> -    memfd = open( "/dev/mem", O_RDONLY | O_CLOEXEC );
> +    memfd = pci_open_cloexec( "/dev/mem", O_RDONLY );
>      if ( memfd == -1 )
>         return errno;
>
> @@ -574,7 +574,7 @@ pci_device_freebsd_open_legacy_io(struct pci_io_handle
> *ret,
>      struct pci_device *dev, pciaddr_t base, pciaddr_t size)
>  {
>  #if defined(__i386__) || defined(__amd64__)
> -       ret->fd = open("/dev/io", O_RDWR | O_CLOEXEC);
> +       ret->fd = pci_open_cloexec("/dev/io", O_RDWR);
>
>         if (ret->fd < 0)
>                 return NULL;
> @@ -735,7 +735,7 @@ pci_system_freebsd_create( void )
>      int i;
>
>      /* Try to open the PCI device */
> -    pcidev = open( "/dev/pci", O_RDWR | O_CLOEXEC );
> +    pcidev = pci_open_cloexec( "/dev/pci", O_RDWR );
>      if ( pcidev == -1 )
>         return ENXIO;
>
> diff --git a/src/linux_sysfs.c b/src/linux_sysfs.c
> index 08c99719bcba..120cd6411893 100644
> --- a/src/linux_sysfs.c
> +++ b/src/linux_sysfs.c
> @@ -100,7 +100,7 @@ pci_system_linux_sysfs_create( void )
>         if ( pci_sys != NULL ) {
>             pci_sys->methods = & linux_sysfs_methods;
>  #ifdef HAVE_MTRR
> -           pci_sys->mtrr_fd = open("/proc/mtrr", O_WRONLY | O_CLOEXEC);
> +           pci_sys->mtrr_fd = pci_open_cloexec("/proc/mtrr", O_WRONLY);
>  #endif
>             err = populate_entries(pci_sys);
>         }
> @@ -247,7 +247,7 @@ pci_device_linux_sysfs_probe( struct pci_device * dev )
>                   dev->bus,
>                   dev->dev,
>                   dev->func );
> -       fd = open( name, O_RDONLY | O_CLOEXEC);
> +       fd = pci_open_cloexec(name, O_RDONLY);
>         if ( fd != -1 ) {
>             char * next;
>             pciaddr_t  low_addr;
> @@ -309,7 +309,7 @@ pci_device_linux_sysfs_read_rom( struct pci_device *
> dev, void * buffer )
>               dev->dev,
>               dev->func );
>
> -    fd = open( name, O_RDWR | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, O_RDWR);
>      if ( fd == -1 ) {
>  #ifdef LINUX_ROM
>         /* If reading the ROM using sysfs fails, fall back to the old
> @@ -390,7 +390,7 @@ pci_device_linux_sysfs_read( struct pci_device * dev,
> void * data,
>               dev->dev,
>               dev->func );
>
> -    fd = open( name, O_RDONLY | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, O_RDONLY);
>      if ( fd == -1 ) {
>         return errno;
>      }
> @@ -450,7 +450,7 @@ pci_device_linux_sysfs_write( struct pci_device * dev,
> const void * data,
>               dev->dev,
>               dev->func );
>
> -    fd = open( name, O_WRONLY | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, O_WRONLY);
>      if ( fd == -1 ) {
>         return errno;
>      }
> @@ -501,7 +501,7 @@ pci_device_linux_sysfs_map_range_wc(struct pci_device
> *dev,
>              dev->dev,
>              dev->func,
>              map->region);
> -    fd = open(name, open_flags | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, open_flags);
>      if (fd == -1)
>             return errno;
>
> @@ -566,7 +566,7 @@ pci_device_linux_sysfs_map_range(struct pci_device
> *dev,
>               dev->func,
>               map->region);
>
> -    fd = open(name, open_flags | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, open_flags);
>      if (fd == -1) {
>          return errno;
>      }
> @@ -689,7 +689,7 @@ static void pci_device_linux_sysfs_enable(struct
> pci_device *dev)
>               dev->dev,
>               dev->func );
>
> -    fd = open( name, O_RDWR | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, O_RDWR);
>      if (fd == -1)
>         return;
>
> @@ -711,7 +711,7 @@ static int pci_device_linux_sysfs_boot_vga(struct
> pci_device *dev)
>               dev->dev,
>               dev->func );
>
> -    fd = open( name, O_RDONLY | O_CLOEXEC);
> +    fd = pci_open_cloexec(name, O_RDONLY);
>      if (fd == -1)
>         return 0;
>
> @@ -754,7 +754,7 @@ pci_device_linux_sysfs_open_device_io(struct
> pci_io_handle *ret,
>      snprintf(name, PATH_MAX, "%s/%04x:%02x:%02x.%1u/resource%d",
>              SYS_BUS_PCI, dev->domain, dev->bus, dev->dev, dev->func, bar);
>
> -    ret->fd = open(name, O_RDWR | O_CLOEXEC);
> +    ret->fd = pci_open_cloexec(name, O_RDWR);
>
>      if (ret->fd < 0)
>         return NULL;
> @@ -778,7 +778,7 @@ pci_device_linux_sysfs_open_legacy_io(struct
> pci_io_handle *ret,
>         snprintf(name, PATH_MAX, "/sys/class/pci_bus/%04x:%02x/legacy_io",
>                  dev->domain, dev->bus);
>
> -       ret->fd = open(name, O_RDWR | O_CLOEXEC);
> +       ret->fd = pci_open_cloexec(name, O_RDWR);
>         if (ret->fd >= 0)
>             break;
>
> @@ -925,7 +925,7 @@ pci_device_linux_sysfs_map_legacy(struct pci_device
> *dev, pciaddr_t base,
>         snprintf(name, PATH_MAX, "/sys/class/pci_bus/%04x:%02x/legacy_mem",
>                  dev->domain, dev->bus);
>
> -       fd = open(name, flags | O_CLOEXEC);
> +       fd = pci_open_cloexec(name, flags);
>         if (fd >= 0)
>             break;
>
> @@ -934,7 +934,7 @@ pci_device_linux_sysfs_map_legacy(struct pci_device
> *dev, pciaddr_t base,
>
>      /* If not, /dev/mem is the best we can do */
>      if (!dev)
> -       fd = open("/dev/mem", flags | O_CLOEXEC);
> +       fd = pci_open_cloexec("/dev/mem", flags);
>
>      if (fd < 0)
>         return errno;
> diff --git a/src/netbsd_pci.c b/src/netbsd_pci.c
> index 52591b08f737..87bb2feb2504 100644
> --- a/src/netbsd_pci.c
> +++ b/src/netbsd_pci.c
> @@ -909,7 +909,7 @@ pci_system_netbsd_create(void)
>         ndevs = 0;
>         nbuses = 0;
>         snprintf(netbsd_devname, 32, "/dev/pci%d", nbuses);
> -       pcifd = open(netbsd_devname, O_RDWR | O_CLOEXEC);
> +       pcifd = pci_open_cloexec(netbsd_devname, O_RDWR);
>         while (pcifd > 0) {
>                 ioctl(pcifd, PCI_IOC_BUSINFO, &businfo);
>                 buses[nbuses].fd = pcifd;
> diff --git a/src/openbsd_pci.c b/src/openbsd_pci.c
> index fe034f3b046b..3d66598b5b77 100644
> --- a/src/openbsd_pci.c
> +++ b/src/openbsd_pci.c
> @@ -571,7 +571,7 @@ pci_system_openbsd_create(void)
>
>         for (domain = 0; domain < sizeof(pcifd) / sizeof(pcifd[0]);
> domain++) {
>                 snprintf(path, sizeof(path), "/dev/pci%d", domain);
> -               pcifd[domain] = open(path, O_RDWR | O_CLOEXEC);
> +               pcifd[domain] = pci_open_cloexec(path, O_RDWR);
>                 if (pcifd[domain] == -1)
>                         break;
>                 ndomains++;
> diff --git a/src/pciaccess_private.h b/src/pciaccess_private.h
> index 9f4e8f9ab573..0de989bceab4 100644
> --- a/src/pciaccess_private.h
> +++ b/src/pciaccess_private.h
> @@ -40,13 +40,16 @@
>  /*
>   * O_CLOEXEC fixes an fd leak case (see 'man 2 open' for details). I don't
>   * know of any OS we support where this isn't available in a sufficiently
> - * new version, so warn unconditionally.
> + * new version, so fail if ALLOW_NO_O_CLOEXEC is not defined.
>   */
>  #include <sys/fcntl.h>
>
> -#ifndef O_CLOEXEC
> -#warning O_CLOEXEC not available, please upgrade.
> -#define O_CLOEXEC 0
> +#if !defined(O_CLOEXEC)
> +# if defined(ALLOW_NO_O_CLOEXEC)
> +#  include <unistd.h>
> +# else
> +#  error O_CLOEXEC not available, please upgrade.
> +# endif
>  #endif
>
>
> @@ -191,3 +194,25 @@ extern void pci_system_openbsd_init_dev_mem( int );
>  extern int pci_system_solx_devfs_create( void );
>  extern int pci_system_x86_create( void );
>  extern void pci_io_cleanup( void );
> +
> +static inline int pci_open_cloexec( const char *path, int flags )
> +{
> +#if defined(O_CLOEXEC)
> +    return open(path, flags | O_CLOEXEC);
> +#else
> +    int fd = open(path, flags);
> +    if (fd >= 0) {
> +       int flags = fcntl(fd, F_GETFD);
> +       if (flags == -1) {
> +           close(fd);
> +           return -1;
> +       }
> +       flags |= FD_CLOEXEC;
> +       if (fcntl(fd, F_SETFD, flags) == -1) {
> +           close(fd);
> +           return -1;
> +       }
> +    }
> +    return fd;
> +#endif
> +}
> diff --git a/src/solx_devfs.c b/src/solx_devfs.c
> index f57239304a43..2d4b102f8cf1 100644
> --- a/src/solx_devfs.c
> +++ b/src/solx_devfs.c
> @@ -415,7 +415,7 @@ probe_nexus_node(di_node_t di_node, di_minor_t minor,
> void *arg)
>             nexus_path, first_bus, last_bus);
>  #endif
>
> -    if ((fd = open(nexus_path, O_RDWR | O_CLOEXEC)) >= 0) {
> +    if ((fd = pci_open_cloexec(nexus_path, O_RDWR)) >= 0) {
>         probe_args_t args;
>
>         nexus->fd = fd;
> @@ -718,7 +718,7 @@ pci_device_solx_devfs_map_range(struct pci_device *dev,
>  #endif
>
>      if (map_fd < 0) {
> -       if ((map_fd = open(map_dev, O_RDWR | O_CLOEXEC)) < 0) {
> +       if ((map_fd = pci_open_cloexec(map_dev, O_RDWR)) < 0) {
>             err = errno;
>             (void) fprintf(stderr, "can not open %s: %s\n", map_dev,
>                            strerror(errno));
> diff --git a/src/x86_pci.c b/src/x86_pci.c
> index 49c1cabc3c6c..7088ff9a016d 100644
> --- a/src/x86_pci.c
> +++ b/src/x86_pci.c
> @@ -457,7 +457,7 @@ pci_device_x86_read_rom(struct pci_device *dev, void
> *buffer)
>         return ENOSYS;
>      }
>
> -    memfd = open("/dev/mem", O_RDONLY | O_CLOEXEC);
> +    memfd = pci_open_cloexec("/dev/mem", O_RDONLY);
>      if (memfd == -1)
>         return errno;
>
> @@ -637,7 +637,7 @@ static int
>  pci_device_x86_map_range(struct pci_device *dev,
>      struct pci_device_mapping *map)
>  {
> -    int memfd = open("/dev/mem", O_RDWR | O_CLOEXEC);
> +    int memfd = pci_open_cloexec("/dev/mem", O_RDWR);
>      int prot = PROT_READ;
>
>      if (memfd == -1)
> --
> 2.1.0
>
> _______________________________________________
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>



-- 
  Jasper
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