evdev: decode struct input_absinfo regardless of in-kernel definitions

[strace] / evdev.c

diff --git a/evdev.c b/evdev.c
index 62a2226335321c6ebf342cf7c97074db95f1e693..72addff6c8a80338c2587bdfc31b8521b796ca0e 100644 (file)
--- a/evdev.c
+++ b/evdev.c
@@ -37,6 +37,15 @@
 #  define SYN_MAX 0xf
 # endif
 
+typedef struct {
+       int32_t value;
+       int32_t minimum;
+       int32_t maximum;
+       int32_t fuzz;
+       int32_t flat;
+       int32_t resolution; /**< Added by Linux commit v2.6.31-rc1~100^2~1 */
+} struct_input_absinfo;
+
 /** Added by Linux commit v2.6.37-rc1~5^2~3^2~47 */
 typedef struct {
        uint8_t  flags;
@@ -53,6 +62,9 @@ typedef struct {
        uint64_t codes_ptr;
 } struct_input_mask;
 
+static_assert(sizeof(struct input_absinfo) <= sizeof(struct_input_absinfo),
+             "Unexpected struct input_absinfo size, please update "
+             "the decoder");
 # ifdef HAVE_STRUCT_INPUT_KEYMAP_ENTRY
 static_assert(sizeof(struct input_keymap_entry)
              == sizeof(struct_input_keymap_entry),
@@ -83,36 +95,50 @@ static_assert(sizeof(struct input_mask) == sizeof(struct_input_mask),
 # endif
 
 static int
-abs_ioctl(struct tcb *const tcp, const kernel_ulong_t arg)
+abs_ioctl(struct tcb *const tcp, const unsigned int code,
+         const kernel_ulong_t arg)
 {
+       static const size_t orig_sz = offsetofend(struct_input_absinfo, flat);
+       static const size_t res_sz = offsetofend(struct_input_absinfo,
+                                                resolution);
+
+       struct_input_absinfo absinfo;
+       size_t sz = _IOC_SIZE(code);
+       size_t read_sz = MIN(sz, sizeof(absinfo));
+
+       if (sz < orig_sz)
+               return RVAL_DECODED;
+
        tprints(", ");
 
-       struct input_absinfo absinfo;
-
-       if (!umove_or_printaddr(tcp, arg, &absinfo)) {
-               tprintf("{value=%u"
-                       ", minimum=%u, ",
-                       absinfo.value,
-                       absinfo.minimum);
-
-               if (!abbrev(tcp)) {
-                       tprintf("maximum=%u"
-                               ", fuzz=%u"
-                               ", flat=%u",
-                               absinfo.maximum,
-                               absinfo.fuzz,
-                               absinfo.flat);
-# ifdef HAVE_STRUCT_INPUT_ABSINFO_RESOLUTION
-                       tprintf(", resolution=%u",
-                               absinfo.resolution);
-# endif
-               } else {
-                       tprints("...");
-               }
+       if (umoven_or_printaddr(tcp, arg, read_sz, &absinfo))
+               return RVAL_IOCTL_DECODED;
+
+       tprintf("{value=%u"
+               ", minimum=%u, ",
+               absinfo.value,
+               absinfo.minimum);
 
-               tprints("}");
+       if (!abbrev(tcp)) {
+               tprintf("maximum=%u"
+                       ", fuzz=%u"
+                       ", flat=%u",
+                       absinfo.maximum,
+                       absinfo.fuzz,
+                       absinfo.flat);
+               if (sz >= res_sz) {
+                       tprintf(", resolution=%u%s",
+                               absinfo.resolution,
+                               sz > res_sz ? ", ..." : "");
+               } else if (sz > orig_sz) {
+                       tprints(", ...");
+               }
+       } else {
+               tprints("...");
        }
 
+       tprints("}");
+
        return RVAL_IOCTL_DECODED;
 }
 
@@ -402,7 +428,7 @@ evdev_read_ioctl(struct tcb *const tcp, const unsigned int code,
 
        /* multi-number fixed-length commands */
        if ((_IOC_NR(code) & ~ABS_MAX) == _IOC_NR(EVIOCGABS(0)))
-               return abs_ioctl(tcp, arg);
+               return abs_ioctl(tcp, code, arg);
 
        /* multi-number variable-length commands */
        if ((_IOC_NR(code) & ~EV_MAX) == _IOC_NR(EVIOCGBIT(0, 0)))
@@ -443,7 +469,7 @@ evdev_write_ioctl(struct tcb *const tcp, const unsigned int code,
 
        /* multi-number fixed-length commands */
        if ((_IOC_NR(code) & ~ABS_MAX) == _IOC_NR(EVIOCSABS(0)))
-               return abs_ioctl(tcp, arg);
+               return abs_ioctl(tcp, code, arg);
 
        return 0;
 }