| 1 | /* |
| 2 | * Hosted file support for semihosting syscalls. |
| 3 | * |
| 4 | * Copyright (c) 2005, 2007 CodeSourcery. |
| 5 | * Copyright (c) 2019 Linaro |
| 6 | * Copyright © 2020 by Keith Packard <keithp@keithp.com> |
| 7 | * |
| 8 | * SPDX-License-Identifier: GPL-2.0-or-later |
| 9 | */ |
| 10 | |
| 11 | #include "qemu/osdep.h" |
| 12 | #include "gdbstub/syscalls.h" |
| 13 | #include "semihosting/semihost.h" |
| 14 | #include "semihosting/guestfd.h" |
| 15 | |
| 16 | static GArray *guestfd_array; |
| 17 | |
| 18 | void qemu_semihosting_guestfd_init(void) |
| 19 | { |
| 20 | /* New entries zero-initialized, i.e. type GuestFDUnused */ |
| 21 | guestfd_array = g_array_new(FALSE, TRUE, sizeof(GuestFD)); |
| 22 | |
| 23 | if (semihosting_arm_compatible()) { |
| 24 | semihosting_arm_compatible_init(); |
| 25 | return; |
| 26 | } |
| 27 | |
| 28 | /* Out of ARM, the stdio file descriptors apply. */ |
| 29 | guestfd_array = g_array_set_size(guestfd_array, 3); |
| 30 | #ifndef CONFIG_USER_ONLY |
| 31 | if (!use_gdb_syscalls()) { |
| 32 | GuestFD *gf = &g_array_index(guestfd_array, GuestFD, 0); |
| 33 | gf[0].type = GuestFDConsole; |
| 34 | gf[1].type = GuestFDConsole; |
| 35 | gf[2].type = GuestFDConsole; |
| 36 | return; |
| 37 | } |
| 38 | #endif |
| 39 | associate_guestfd(0, 0); |
| 40 | associate_guestfd(1, 1); |
| 41 | associate_guestfd(2, 2); |
| 42 | } |
| 43 | |
| 44 | /* |
| 45 | * Allocate a new guest file descriptor and return it; if we |
| 46 | * couldn't allocate a new fd then return -1. |
| 47 | * This is a fairly simplistic implementation because we don't |
| 48 | * expect that most semihosting guest programs will make very |
| 49 | * heavy use of opening and closing fds. |
| 50 | */ |
| 51 | int alloc_guestfd(void) |
| 52 | { |
| 53 | guint i; |
| 54 | |
| 55 | /* SYS_OPEN should return nonzero handle on success. Start guestfd from 1 */ |
| 56 | for (i = 1; i < guestfd_array->len; i++) { |
| 57 | GuestFD *gf = &g_array_index(guestfd_array, GuestFD, i); |
| 58 | |
| 59 | if (gf->type == GuestFDUnused) { |
| 60 | return i; |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | /* All elements already in use: expand the array */ |
| 65 | g_array_set_size(guestfd_array, i + 1); |
| 66 | return i; |
| 67 | } |
| 68 | |
| 69 | static void do_dealloc_guestfd(GuestFD *gf) |
| 70 | { |
| 71 | gf->type = GuestFDUnused; |
| 72 | } |
| 73 | |
| 74 | /* |
| 75 | * Look up the guestfd in the data structure; return NULL |
| 76 | * for out of bounds, but don't check whether the slot is unused. |
| 77 | * This is used internally by the other guestfd functions. |
| 78 | */ |
| 79 | static GuestFD *do_get_guestfd(int guestfd) |
| 80 | { |
| 81 | if (guestfd < 0 || guestfd >= guestfd_array->len) { |
| 82 | return NULL; |
| 83 | } |
| 84 | |
| 85 | return &g_array_index(guestfd_array, GuestFD, guestfd); |
| 86 | } |
| 87 | |
| 88 | /* |
| 89 | * Given a guest file descriptor, get the associated struct. |
| 90 | * If the fd is not valid, return NULL. This is the function |
| 91 | * used by the various semihosting calls to validate a handle |
| 92 | * from the guest. |
| 93 | * Note: calling alloc_guestfd() or dealloc_guestfd() will |
| 94 | * invalidate any GuestFD* obtained by calling this function. |
| 95 | */ |
| 96 | GuestFD *get_guestfd(int guestfd) |
| 97 | { |
| 98 | GuestFD *gf = do_get_guestfd(guestfd); |
| 99 | |
| 100 | if (!gf || gf->type == GuestFDUnused) { |
| 101 | return NULL; |
| 102 | } |
| 103 | return gf; |
| 104 | } |
| 105 | |
| 106 | /* |
| 107 | * Associate the specified guest fd (which must have been |
| 108 | * allocated via alloc_fd() and not previously used) with |
| 109 | * the specified host/gdb fd. |
| 110 | */ |
| 111 | void associate_guestfd(int guestfd, int hostfd) |
| 112 | { |
| 113 | GuestFD *gf = do_get_guestfd(guestfd); |
| 114 | |
| 115 | assert(gf); |
| 116 | gf->type = use_gdb_syscalls() ? GuestFDGDB : GuestFDHost; |
| 117 | gf->hostfd = hostfd; |
| 118 | } |
| 119 | |
| 120 | void staticfile_guestfd(int guestfd, const uint8_t *data, size_t len) |
| 121 | { |
| 122 | GuestFD *gf = do_get_guestfd(guestfd); |
| 123 | |
| 124 | assert(gf); |
| 125 | gf->type = GuestFDStatic; |
| 126 | gf->staticfile.data = data; |
| 127 | gf->staticfile.len = len; |
| 128 | gf->staticfile.off = 0; |
| 129 | } |
| 130 | |
| 131 | /* |
| 132 | * Deallocate the specified guest file descriptor. This doesn't |
| 133 | * close the host fd, it merely undoes the work of alloc_fd(). |
| 134 | */ |
| 135 | void dealloc_guestfd(int guestfd) |
| 136 | { |
| 137 | GuestFD *gf = do_get_guestfd(guestfd); |
| 138 | |
| 139 | assert(gf); |
| 140 | do_dealloc_guestfd(gf); |
| 141 | } |