Squash some GCC warnings that only appear when compiling with optimiz…

…ation
newbiecodingman · May 31, 2020 · e3c1346 · e3c1346
1 parent 9381dc2
commit e3c1346
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Showing 10 changed files with 23 additions and 12 deletions.
diff --git a/emu/float80-test.c b/emu/float80-test.c
@@ -1,4 +1,5 @@
 #include <stdio.h>
+#include <stdlib.h>
 #include <stdarg.h>
 #include <math.h>
 #include <fenv.h>
@@ -37,6 +38,7 @@ void _suite_start(const char *suite) {
         case FE_DOWNWARD: rounding_mode_str = "down"; break;
         case FE_UPWARD: rounding_mode_str = "up"; break;
         case FE_TOWARDZERO: rounding_mode_str = "towards zero"; break;
+        default: abort();
     }
     printf("==== %s, round %s ====\n", suite, rounding_mode_str);
     suite_passed = 0;

diff --git a/emu/memory.c b/emu/memory.c
@@ -81,7 +81,7 @@ void mem_next_page(struct mem *mem, page_t *page) {
 }
 
 page_t pt_find_hole(struct mem *mem, pages_t size) {
-    page_t hole_end;
+    page_t hole_end = 0; // this can never be used before initializing but gcc doesn't realize
     bool in_hole = false;
     for (page_t page = 0xf7ffd; page > 0x40000; page--) {
         // I don't know how this works but it does

diff --git a/fs/generic.c b/fs/generic.c
@@ -110,7 +110,7 @@ int generic_getpath(struct fd *fd, char *buf) {
     if (strlen(buf) + strlen(fd->mount->point) >= MAX_PATH)
         return _ENAMETOOLONG;
     memmove(buf + strlen(fd->mount->point), buf, strlen(buf) + 1);
-    strncpy(buf, fd->mount->point, strlen(fd->mount->point));
+    memcpy(buf, fd->mount->point, strlen(fd->mount->point));
     if (buf[0] == '\0')
         strcpy(buf, "/");
     return 0;

diff --git a/fs/lock.c b/fs/lock.c
@@ -158,7 +158,8 @@ static int file_lock_from_flock(struct fd *fd, struct flock_ *flock, struct file
             offset = stat.size;
             break;
         }
-
+        default:
+            return _EINVAL;
     }
 
     lock->start = flock->start + offset;

diff --git a/fs/real.c b/fs/real.c
@@ -401,6 +401,7 @@ int realfs_fsetattr(struct fd *fd, struct attr attr) {
         case attr_size:
             err = ftruncate(real_fd, attr.size);
             break;
+        default: abort();
     }
     if (err < 0)
         return errno_map();

diff --git a/kernel/exec.c b/kernel/exec.c
@@ -203,7 +203,7 @@ static int elf_exec(struct fd *fd, const char *file, struct exec_args argv, stru
 
     current->mm->exefile = fd_retain(fd);
 
-    addr_t load_addr; // used for AX_PHDR
+    addr_t load_addr = 0; // used for AX_PHDR
     bool load_addr_set = false;
     addr_t bias = 0; // offset for loading shared libraries as executables
 

diff --git a/kernel/task.h b/kernel/task.h
@@ -30,7 +30,7 @@ struct task {
 #define MAX_GROUPS 32
     unsigned ngroups;
     uid_t_ groups[MAX_GROUPS];
-    char comm[16];
+    char comm[16] __strncpy_safe;
     bool did_exec; // for that one annoying setsid edge case
 
     struct fdtable *files;

diff --git a/misc.h b/misc.h
@@ -53,7 +53,14 @@
 #define __no_instrument
 #endif
 
+#if is_gcc(8)
+#define __strncpy_safe __attribute__((nonstring))
+#else
+#define __strncpy_safe
+#endif
+
 #define zero_init(type) ((type[1]){}[0])
+#define pun(type, x) (((union {typeof(x) _; type a;}) (x)).a)
 
 #define UNUSED(x) UNUSED_##x __attribute__((unused))
 static inline void __use(int dummy __attribute__((unused)), ...) {}

diff --git a/tools/ptraceomatic.c b/tools/ptraceomatic.c
@@ -92,8 +92,8 @@ static int compare_cpus(struct cpu_state *cpu, struct tlb *tlb, int pid, int und
         return -1;
     }
 #define CHECK_XMMREG(i) \
-    CHECK(*(uint64_t *) &fpregs.xmm_space[i * 4],   cpu->xmm[i].qw[0], "xmm" #i " low") \
-    CHECK(*(uint64_t *) &fpregs.xmm_space[i*4+2], cpu->xmm[i].qw[1], "xmm" #i " high")
+    CHECK(pun(uint64_t, fpregs.xmm_space[i * 4]), cpu->xmm[i].qw[0], "xmm" #i " low") \
+    CHECK(pun(uint64_t, fpregs.xmm_space[i*4+2]), cpu->xmm[i].qw[1], "xmm" #i " high")
     CHECK_XMMREG(0);
     CHECK_XMMREG(1);
     CHECK_XMMREG(2);
@@ -109,8 +109,8 @@ static int compare_cpus(struct cpu_state *cpu, struct tlb *tlb, int pid, int und
     fpregs.swd &= FSW_MASK;
 
 #define CHECK_FPREG(i) \
-    CHECK(*(uint64_t *) &fpregs.st_space[i * 4], cpu->fp[(cpu->top + i)%8].signif,  "st(" #i ") signif") \
-    CHECK(*(uint16_t *) &fpregs.st_space[i*4+2], cpu->fp[(cpu->top + i)%8].signExp, "st(" #i ") sign/exp")
+    CHECK(pun(uint64_t, fpregs.st_space[i * 4]), cpu->fp[(cpu->top + i)%8].signif,  "st(" #i ") signif") \
+    CHECK(pun(uint16_t, fpregs.st_space[i*4+2]), cpu->fp[(cpu->top + i)%8].signExp, "st(" #i ") sign/exp")
     CHECK_FPREG(0);
     CHECK_FPREG(1);
     CHECK_FPREG(2);

diff --git a/tools/undefined-flags.c b/tools/undefined-flags.c
@@ -26,7 +26,7 @@ int undefined_flags_mask(struct cpu_state *cpu, struct tlb *tlb) {
                 case 0xac:
                 case 0xad: {
                     ip++;
-                    byte_t shift;
+                    byte_t shift = -1;
                     if (opcode == 0xad)
                         shift = cpu->cl;
                     else
@@ -52,7 +52,7 @@ int undefined_flags_mask(struct cpu_state *cpu, struct tlb *tlb) {
         case 0xd2:
         case 0xd3: {
             ip++; // skip modrm
-            byte_t shift_count;
+            byte_t shift_count = -1;
             if (opcode == 0xd0 || opcode == 0xd1)
                 shift_count = 1;
             else if (opcode == 0xd2 || opcode == 0xd3)
@@ -66,7 +66,7 @@ int undefined_flags_mask(struct cpu_state *cpu, struct tlb *tlb) {
 
         case 0xf6: case 0xf7: {
             // group 3
-            byte_t modrm;
+            byte_t modrm = -1;
             read(modrm);
             switch (REG(modrm)) {
                 case 4: return S|Z|A|P; // mul